Rolling v8/build: https://chromium.googlesource.com/chromium/src/build/+log/a312720..2a0adf9

Rolling v8/third_party/catapult: https://chromium.googlesource.com/external/github.com/catapult-project/catapult/+log/b3c4635..80a58af

TBR=machenbach@chromium.org,vogelheim@chromium.org,hablich@chromium.org

Change-Id: I4f8940455493f1fb2360cb5ee0401b0f68894854
Reviewed-on: https://chromium-review.googlesource.com/469467Reviewed-by: v8 autoroll <v8-autoroll@chromium.org>
Commit-Queue: v8 autoroll <v8-autoroll@chromium.org>
Cr-Commit-Position: refs/heads/master@{#44423}

Revert of [snapshot] Move builtins generation into mksnapshot (patchset #8 id:160001 of https://codereview.chromium.org/2760233005/ )

Reason for revert:
I think that this CL breaks chromium compilation on windows with clang (). All other CLs in the list looks trivial and don't change test/unittest/BUILD.gn.

[42456/47924] CXX obj/v8/test/unittests/unittests/value-serializer-unittest.obj
[42457/47924] LINK unittests.exe unittests.exe.pdb
FAILED: unittests.exe unittests.exe.pdb
E:/b/depot_tools/python276_bin/python.exe ../../build/toolchain/win/tool_wrapper.py link-wrapper environment.x64 False link.exe /nologo /OUT:./unittests.exe /PDB:./unittests.exe.pdb @./unittests.exe.rsp
bitmap-unittest.obj : error LNK2019: unresolved external symbol "public: void __cdecl v8::internal::List<class v8::internal::AllocationObserver *,class v8::internal::FreeStoreAllocationPolicy>::Add(class v8::internal::AllocationObserver * const &,class v8::internal::FreeStoreAllocationPolicy)" (?Add@?$List@PEAVAllocationObserver@internal@v8@@VFreeStoreAllocationPolicy@23@@internal@v8@@QEAAXAEBQEAVAllocationObserver@23@VFreeStoreAllocationPolicy@23@@Z) referenced in function "public: virtual void __cdecl v8::internal::Space::AddAllocationObserver(class v8::internal::AllocationObserver *)" (?AddAllocationObserver@Space@internal@v8@@UEAAXPEAVAllocationObserver@23@@Z)

slot-set-unittest.obj : error LNK2001: unresolved external symbol "public: void __cdecl v8::internal::List<class v8::internal::AllocationObserver *,class v8::internal::FreeStoreAllocationPolicy>::Add(class v8::internal::AllocationObserver * const &,class v8::internal::FreeStoreAllocationPolicy)" (?Add@?$List@PEAVAllocationObserver@internal@v8@@VFreeStoreAllocationPolicy@23@@internal@v8@@QEAAXAEBQEAVAllocationObserver@23@VFreeStoreAllocationPolicy@23@@Z)

bitmap-unittest.obj : error LNK2019: unresolved external symbol "public: bool __cdecl v8::internal::List<class v8::internal::AllocationObserver *,class v8::internal::FreeStoreAllocationPolicy>::RemoveElement(class v8::internal::AllocationObserver * const &)" (?RemoveElement@?$List@PEAVAllocationObserver@internal@v8@@VFreeStoreAllocationPolicy@23@@internal@v8@@QEAA_NAEBQEAVAllocationObserver@23@@Z) referenced in function "public: virtual void __cdecl v8::internal::Space::RemoveAllocationObserver(class v8::internal::AllocationObserver *)" (?RemoveAllocationObserver@Space@internal@v8@@UEAAXPEAVAllocationObserver@23@@Z)

slot-set-unittest.obj : error LNK2001: unresolved external symbol "public: bool __cdecl v8::internal::List<class v8::internal::AllocationObserver *,class v8::internal::FreeStoreAllocationPolicy>::RemoveElement(class v8::internal::AllocationObserver * const &)" (?RemoveElement@?$List@PEAVAllocationObserver@internal@v8@@VFreeStoreAllocationPolicy@23@@internal@v8@@QEAA_NAEBQEAVAllocationObserver@23@@Z)

./unittests.exe : fatal error LNK1120: 2 unresolved externals

Original issue's description:
> [snapshot] Move builtins generation into mksnapshot
>
> and out of the main library. This saves about 5% of binary size
> (800KB on x64, 373KB on android_arm).
>
> Only the GN build is supported; the GYP build is maintained working
> but does not support the feature.
>
> BUG=v8:6055
> CQ_INCLUDE_TRYBOTS=master.tryserver.v8:v8_linux_nosnap_rel;
>
> Review-Url: https://codereview.chromium.org/2760233005
> Cr-Commit-Position: refs/heads/master@{#44412}
> Committed: https://chromium.googlesource.com/v8/v8/+/4782bc0df89ceb127e38017b8dcf531222a0e966

TBR=jgruber@chromium.org,rmcilroy@chromium.org,machenbach@chromium.org,jkummerow@chromium.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=v8:6055

Review-Url: https://codereview.chromium.org/2803903002
Cr-Commit-Position: refs/heads/master@{#44422}

Bug: v8:6154
NOTRY=true

Change-Id: I877dfdbab01df6356e83ee81ca75d54a951b9cab
Reviewed-on: https://chromium-review.googlesource.com/468886Reviewed-by: Franziska Hinkelmann <franzih@chromium.org>
Commit-Queue: Michael Achenbach <machenbach@chromium.org>
Cr-Commit-Position: refs/heads/master@{#44421}

Revert of [build] Temporarily switch off goma on gyp bot (patchset #1 id:1 of https://codereview.chromium.org/2802793002/ )

Reason for revert:
A different sysroot config fix was required here.

Original issue's description:
> [build] Temporarily switch off goma on gyp bot
>
> BUG=chromium:708482
> NOTRY=true
> TBR=tandrii@chromium.org
>
> Review-Url: https://codereview.chromium.org/2802793002
> Cr-Commit-Position: refs/heads/master@{#44418}
> Committed: https://chromium.googlesource.com/v8/v8/+/6cf74cb61b0f0e50a42b9fbe2b3d1f3c3dcfc14e

TBR=tandrii@chromium.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=chromium:708482

Review-Url: https://codereview.chromium.org/2799083002
Cr-Commit-Position: refs/heads/master@{#44420}

BUG=chromium:708482
NOTRY=true
TBR=thakis@chromium.org

Review-Url: https://codereview.chromium.org/2798133002
Cr-Commit-Position: refs/heads/master@{#44419}

BUG=chromium:708482
NOTRY=true
TBR=tandrii@chromium.org

Review-Url: https://codereview.chromium.org/2802793002
Cr-Commit-Position: refs/heads/master@{#44418}

Bug: chromium:645890
Change-Id: I9856712ca8694b3447a611c3555c42145f449b11
Reviewed-on: https://chromium-review.googlesource.com/464726Reviewed-by: Yang Guo <yangguo@chromium.org>
Reviewed-by: Aleksey Kozyatinskiy <kozyatinskiy@chromium.org>
Commit-Queue: Michael Achenbach <machenbach@chromium.org>
Cr-Commit-Position: refs/heads/master@{#44417}

What will we get:
- console would be included into snapshot and allow us to reduce time that we spent in contextCreated function (~5 times faster),
- it allows us to make further small improvement of console methods, e.g. we can implement super quick return from console.assert if first argument is true,
- console calls are ~ 15% faster.

BUG=v8:6175
R=dgozman@chromium.org

Review-Url: https://codereview.chromium.org/2785293002
Cr-Original-Original-Commit-Position: refs/heads/master@{#44353}
Committed: https://chromium.googlesource.com/v8/v8/+/55905f85d63d75aaa9313e51eb7bede754a8e41c
Review-Url: https://codereview.chromium.org/2785293002
Cr-Original-Commit-Position: refs/heads/master@{#44355}
Committed: https://chromium.googlesource.com/v8/v8/+/cc74ea0bc4fe4a71fa53d08b62cc18d15e01fbb3
Review-Url: https://codereview.chromium.org/2785293002
Cr-Commit-Position: refs/heads/master@{#44416}

Move the ToBoolean elision in the BytecodeGenerator instead of the
peephole optimizer. Adds a TypeHint mechanism to the ExpressionResult
to enable passing of type hints through the ast visitor.

BUG=v8:6194

Change-Id: Ic55506ba11b213f7459250004d3f18cab04ee9b3
Reviewed-on: https://chromium-review.googlesource.com/467208
Commit-Queue: Ross McIlroy <rmcilroy@chromium.org>
Reviewed-by: Yang Guo <yangguo@chromium.org>
Reviewed-by: Leszek Swirski <leszeks@chromium.org>
Cr-Commit-Position: refs/heads/master@{#44415}

This fixes a corner case which allowed warnings during the asm.js
instantiation to be promoted to actual exceptions. Even instantiation
attempts that fail are not allowed to throw exceptions observable by
JavaScript, but need to fall back to JavaScript execution.

R=clemensh@chromium.org
TEST=mjsunit/regress/regress-6203
BUG=v8:6203

Change-Id: I86f5a3adda4bcfe63b5cddc42d8ae1c3dbb88147
Reviewed-on: https://chromium-review.googlesource.com/468808
Commit-Queue: Michael Starzinger <mstarzinger@chromium.org>
Reviewed-by: Clemens Hammacher <clemensh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#44414}

DCHECK disappears on release build.

R=joransiu@ca.ibm.com, bjaideep@ca.ibm.com
BUG=

Review-Url: https://codereview.chromium.org/2803663002
Cr-Commit-Position: refs/heads/master@{#44413}

and out of the main library. This saves about 5% of binary size
(800KB on x64, 373KB on android_arm).

Only the GN build is supported; the GYP build is maintained working
but does not support the feature.

BUG=v8:6055
CQ_INCLUDE_TRYBOTS=master.tryserver.v8:v8_linux_nosnap_rel;

Review-Url: https://codereview.chromium.org/2760233005
Cr-Commit-Position: refs/heads/master@{#44412}

It enables jobs without a SharedFunctionInfo.

BUG=v8:6093

Change-Id: I70e226638fdb5b3a0634cc4437d128771c838eee
Reviewed-on: https://chromium-review.googlesource.com/468966Reviewed-by: Marja Hölttä <marja@chromium.org>
Reviewed-by: Jochen Eisinger <jochen@chromium.org>
Reviewed-by: Ross McIlroy <rmcilroy@chromium.org>
Commit-Queue: Wiktor Garbacz <wiktorg@google.com>
Cr-Commit-Position: refs/heads/master@{#44411}

There's no need to set it so early - it's only needed when the function has
really been parsed. This way we don't need to produce and store it for skipped
inner functions.

BUG=v8:5516

Change-Id: Ibf59a8acb886ea3de9be140431a334a03b408f5b
Reviewed-on: https://chromium-review.googlesource.com/461827
Commit-Queue: Marja Hölttä <marja@chromium.org>
Reviewed-by: Daniel Vogelheim <vogelheim@chromium.org>
Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
Cr-Commit-Position: refs/heads/master@{#44410}

This extends the test coverage for source position tracking of ToNumber
conversion to also test conversion to "double" type. It also fixes the
discovered inconsistencies. Note that the conversion to "float" remains
untested as imported functions are not allowed have "float" return type.

R=clemensh@chromium.org
TEST=mjsunit/wasm/asm-wasm-exception-in-tonumber
BUG=v8:6127

Change-Id: I6c59b7a24456a585a814f19a86eb9447ac5098ab
Reviewed-on: https://chromium-review.googlesource.com/467251
Commit-Queue: Michael Starzinger <mstarzinger@chromium.org>
Reviewed-by: Clemens Hammacher <clemensh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#44409}

When passing --trace-opt-verbose print more information about why we
decide not to optimize certain functions.

R=jarin@chromium.org

Review-Url: https://codereview.chromium.org/2800623002
Cr-Commit-Position: refs/heads/master@{#44408}

R=jochen@chromium.org

Change-Id: I34bc156c3c4911ba8511ba9720fb6cc2e3880d7e
Reviewed-on: https://chromium-review.googlesource.com/468888Reviewed-by: Jochen Eisinger <jochen@chromium.org>
Commit-Queue: Andreas Haas <ahaas@chromium.org>
Cr-Commit-Position: refs/heads/master@{#44407}

In the C++ wasm interpreter, we decode LEB encoded immediates each time
we execute the respective instruction. The whole instruction sequence
was validated before, thus we know that all integers are valid.
This CL refactors several Decoder methods to allow for either checked
or unchecked decoding. In the checked case, an error is set if a check
fails, in the unchecked case, a DCHECK will fail.

This improves performance of the interpreter by 20.5%.

R=ahaas@chromium.org
BUG=v8:5822

Change-Id: If69efd4f6fbe19d84bfc2f4aa000f429a8e22bf5
Reviewed-on: https://chromium-review.googlesource.com/468786
Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
Reviewed-by: Andreas Haas <ahaas@chromium.org>
Cr-Commit-Position: refs/heads/master@{#44406}

Both methods decoded a LEB128 encoded integer, but only consume_leb
incremented the pc pointer accordingly.
This CL implements consume_leb by using checked_read_leb.

It also refactors a few things:
1) It removes error_pt, which was only avaible in checked_read_leb.
2) It renames the error method to errorf, since it receives a format
   string. This also avoids a name clash.
3) It implements sign extension directly in checked_read_leb instead of
   doing this in the caller.

R=ahaas@chromium.org
BUG=v8:5822

Change-Id: I8058f57418493861e5df26d4949041f6766d5138
Reviewed-on: https://chromium-review.googlesource.com/467150
Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
Reviewed-by: Andreas Haas <ahaas@chromium.org>
Cr-Commit-Position: refs/heads/master@{#44405}

This reverts commit 4bca9dc7.

Reason for revert: Breaks mips builder:
https://build.chromium.org/p/client.v8.ports/builders/V8%20Mips%20-%20builder/builds/8600

Original change's description:
> [compiler-dispatcher] Use an integer job id.
> 
> It enables jobs without a SharedFunctionInfo.
> 
> BUG=v8:6093
> 
> Change-Id: Icc5f01512c270a55349087d418b6be82ad5c6cb4
> Reviewed-on: https://chromium-review.googlesource.com/467148
> Commit-Queue: Wiktor Garbacz <wiktorg@google.com>
> Reviewed-by: Ross McIlroy <rmcilroy@chromium.org>
> Reviewed-by: Jochen Eisinger <jochen@chromium.org>
> Reviewed-by: Marja Hölttä <marja@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#44402}

TBR=rmcilroy@chromium.org,marja@chromium.org,jochen@chromium.org,rmcilroy@google.com,wiktorg@google.com
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=v8:6093

Change-Id: Ie8d26f4e2d42f67a1cfa91269e80e407ed3f0799
Reviewed-on: https://chromium-review.googlesource.com/468887Reviewed-by: Michael Achenbach <machenbach@chromium.org>
Commit-Queue: Michael Achenbach <machenbach@chromium.org>
Cr-Commit-Position: refs/heads/master@{#44404}

Bug: v8:6154
NOTRY=true
TBR=yangguo@chromium.org

Change-Id: I7acb31abd5571261740fd95eeb58f104c26b192e
Reviewed-on: https://chromium-review.googlesource.com/468807Reviewed-by: Michael Achenbach <machenbach@chromium.org>
Commit-Queue: Michael Achenbach <machenbach@chromium.org>
Cr-Commit-Position: refs/heads/master@{#44403}

It enables jobs without a SharedFunctionInfo.

BUG=v8:6093

Change-Id: Icc5f01512c270a55349087d418b6be82ad5c6cb4
Reviewed-on: https://chromium-review.googlesource.com/467148
Commit-Queue: Wiktor Garbacz <wiktorg@google.com>
Reviewed-by: Ross McIlroy <rmcilroy@chromium.org>
Reviewed-by: Jochen Eisinger <jochen@chromium.org>
Reviewed-by: Marja Hölttä <marja@chromium.org>
Cr-Commit-Position: refs/heads/master@{#44402}

Bug: chromium:706763
Change-Id: Iac91fa538ed61d1c47509f990ee9426b0b3bdc1d
Reviewed-on: https://chromium-review.googlesource.com/467147Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
Commit-Queue: Michael Achenbach <machenbach@chromium.org>
Cr-Commit-Position: refs/heads/master@{#44401}

Broken by https://chromium-review.googlesource.com/c/467486/

R=vogelheim@chromium.org

Bug:

Change-Id: Id4353f880f80b48f61a6be1773ebfed16a25e85a
Reviewed-on: https://chromium-review.googlesource.com/468806Reviewed-by: Michael Achenbach <machenbach@chromium.org>
Reviewed-by: Daniel Vogelheim <vogelheim@chromium.org>
Commit-Queue: Marja Hölttä <marja@chromium.org>
Cr-Commit-Position: refs/heads/master@{#44400}

Bug: v8:6154
NOTRY=true

Change-Id: I7f18efaf2f86b9dfa43f249d817777f19ee29c9b
Reviewed-on: https://chromium-review.googlesource.com/467427Reviewed-by: Franziska Hinkelmann <franzih@chromium.org>
Reviewed-by: Yang Guo <yangguo@chromium.org>
Commit-Queue: Michael Achenbach <machenbach@chromium.org>
Cr-Commit-Position: refs/heads/master@{#44399}

This reverts commit eddf90c4.

BUG=chromium:651354

Review-Url: https://codereview.chromium.org/2792063004
Cr-Commit-Position: refs/heads/master@{#44398}

Bug: v8:6154
NOTRY=true
TBR=yangguo@chromium.org

Change-Id: I29e8fd8e12c43478086a35a28249f5f66cd30b6b
Reviewed-on: https://chromium-review.googlesource.com/467429Reviewed-by: Michael Achenbach <machenbach@chromium.org>
Commit-Queue: Michael Achenbach <machenbach@chromium.org>
Cr-Commit-Position: refs/heads/master@{#44397}

IdentifierStart::Is and IdentifierContinue::Is both return true for '\'.
The reason for this is lost to history.

Special-case '\' in the regexp parser to handle this.

BUG=v8:5437,v8:5868

Review-Url: https://codereview.chromium.org/2795093003
Cr-Commit-Position: refs/heads/master@{#44396}

Better demarcation between what's mutable because it is code-
specialization specific, and what is provided at initialization.

BUG=

Review-Url: https://codereview.chromium.org/2784233004
Cr-Commit-Position: refs/heads/master@{#44395}

Rolling v8/build: https://chromium.googlesource.com/chromium/src/build/+log/58260ed..a312720

Rolling v8/third_party/catapult: https://chromium.googlesource.com/external/github.com/catapult-project/catapult/+log/7726dac..b3c4635

Rolling v8/third_party/instrumented_libraries: https://chromium.googlesource.com/chromium/src/third_party/instrumented_libraries/+log/61065eb..05d5695

TBR=machenbach@chromium.org,vogelheim@chromium.org,hablich@chromium.org

Change-Id: I294769d63e0b53b73260ce824a5a9a4e59728fcb
Reviewed-on: https://chromium-review.googlesource.com/468587Reviewed-by: v8 autoroll <v8-autoroll@chromium.org>
Commit-Queue: v8 autoroll <v8-autoroll@chromium.org>
Cr-Commit-Position: refs/heads/master@{#44394}

Remove destructuring assignments (parsed during arrow function formal
parameters) from queue for rewriting if parsing a lazy top-level arrow function.

Built ontop of https://chromium-review.googlesource.com/c/464769/

BUG=chromium:706234, chromium:706761, v8:6182
R=marja@chromium.org, adamk@chromium.org, vogelheim@chromium.org

Change-Id: Ib35196b907350d1d78e4c3fcbf4cc971bf200948
Reviewed-on: https://chromium-review.googlesource.com/465415
Commit-Queue: Caitlin Potter <caitp@igalia.com>
Reviewed-by: Adam Klein <adamk@chromium.org>
Reviewed-by: Marja Hölttä <marja@chromium.org>
Cr-Commit-Position: refs/heads/master@{#44393}

R=joransiu@ca.ibm.com, bjaideep@ca.ibm.com

Review-Url: https://codereview.chromium.org/2795803003
Cr-Commit-Position: refs/heads/master@{#44392}

This enables clients like IndexedDB to know when the data format version has
decreased (i.e. the user has switched to an earlier version) and deal with the
resulting incompatibility up front.

BUG=chromium:704293

Review-Url: https://codereview.chromium.org/2772723005
Cr-Commit-Position: refs/heads/master@{#44391}

Bug: v8:6186
Change-Id: If460313ee861f826a89bc7390a5e35d43d175622
Reviewed-on: https://chromium-review.googlesource.com/466549Reviewed-by: Jakob Gruber <jgruber@chromium.org>
Commit-Queue: Adam Klein <adamk@chromium.org>
Cr-Commit-Position: refs/heads/master@{#44390}

Also rename "Discard" for clarity.

Bug: v8:6092
Change-Id: I8c299ded920e794418e0619b6958fbef35dfda4e
Reviewed-on: https://chromium-review.googlesource.com/466591Reviewed-by: Marja Hölttä <marja@chromium.org>
Commit-Queue: Adam Klein <adamk@chromium.org>
Cr-Commit-Position: refs/heads/master@{#44389}

After discussion with Chrome reviewers for UMA, it was decided that we
would report array buffer allocation sizes in megabytes (not the log).

They also wanted to wait until there is proof that small array buffer
allocations would flood the histogram. Hence, all allocation sizes are
sampled.

There were several ways we could have added the notion of megabyte
samples to V8 code. None of them are a great fit.  This code simply
provides a local function within the code that needs it.

Other possible solutions but rejected were:

a) Use a subclass of histogram to collect data at the megabyte level.
   It has it's own Add() method that converts the size from bytes to
   megabytes, and then call the generic add method AddSample(). This
   solution appears to follow the conventions of subclasses of class
   Histogram.

b) Use Chrome macros - Rejected because it involves changing the
   counter representation of V8.

c) Add a method AddMegabyteSample() to base class Histogram. Rejected
   because it may get confusing if a lot of different measures are
   added the the base class of histograms.

d) Make method AddSample() virtual and override in the derived
   class. Rejected in that sampling is supposed to be fast, and adding
   a virtual call may be breaking that contract.

d) Do not add a derived class. Rather just do the conversions at the
   call sites. Rejected because this duplicates code, and also makes
   it hard to change assumptions on how to calculate.

For Chromes UMA changes see:

CL: https://codereview.chromium.org/2795463002

BUG=chromium:704922
R=bbudge@chromium.org,bradnelson@chromium.org,mtrofin@chromium.org

Review-Url: https://codereview.chromium.org/2795763002
Cr-Commit-Position: refs/heads/master@{#44388}

This reflects both the contract in blink, as well as what we
plan to do in streamed compilation, where we'll want to lay out
bytes received such that each section and each function body is
contiguous, but they may all be separate - which entails a copy.

BUG=chromium:697028

Review-Url: https://codereview.chromium.org/2797653002
Cr-Commit-Position: refs/heads/master@{#44387}

This reverts commit c766727a.

BUG=chromium:651354

Review-Url: https://codereview.chromium.org/2793323002
Cr-Commit-Position: refs/heads/master@{#44386}

The past re-factoring inadvertently increased memory consumption for
AstConsString. This implements a micro-optimization to revert and slightly
improve beyond the original state.

Example, Zone size for parsing closure.js:
  - 20,999,848 B (before refactoring)
  - 21,651,056 B (after refactoring patch; 3.1% regression)
  - 20,641,320 B (after this CL; 1.7% improvement over original)

(Reason: ZoneLinkedList requires 4 pointers to support
the std::list functionality (Zone*, head/tail ptr, payload ptr).
But since we only append and iterate in order and have the Zone*
available in the context, a super simple linked list (value + next ptr)
saves a bit of memory, especially for the common case of having 0 or 1
string segments.)

BUG=v8:6902, chromium:706935

Review-Url: https://codereview.chromium.org/2792353002
Cr-Commit-Position: refs/heads/master@{#44385}

When emitting a frame, we always push the old frame pointer at offset 0 relative
to the new frame pointer. However, we didn't emit DWARF opcodes to inform perf
of this.

BUG=

Review-Url: https://codereview.chromium.org/2795253002
Cr-Commit-Position: refs/heads/master@{#44384}