This is towards closing the perf gap between the MSVC build (which uses link-
time optimization) and Clang (where LTO isn't ready on Windows yet). We did
a study (see bug) to see which non-inlined functions are hit a lot during render
start-up, and which would be inlined during LTO. This should benefit performance
in all builds which currently don't use LTO (Android, Linux, Mac) as well as
the Win/Clang build.

The binary size of chrome_child.dll increases by 2KB with this.

BUG=chromium:728324
CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.linux:linux_chromium_compile_dbg_ng;master.tryserver.chromium.mac:mac_chromium_compile_dbg_ng

Review-Url: https://codereview.chromium.org/2950993002
Cr-Commit-Position: refs/heads/master@{#46229}