[heap] Remove UMAs for fractions

Spaces sizes will be replaced with absolute values.

Bug: 
Change-Id: I3d9f32b723ad8872a088f436bd279a0a3f66401e
Reviewed-on: https://chromium-review.googlesource.com/680769Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Commit-Queue: Michael Lippautz <mlippautz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#48129}

src/counters.h

@@ -1100,13 +1100,7 @@ class RuntimeCallTimerScope {
   HP(external_fragmentation_code_space,                                        \
      V8.MemoryExternalFragmentationCodeSpace)                                  \
   HP(external_fragmentation_map_space, V8.MemoryExternalFragmentationMapSpace) \
-  HP(external_fragmentation_lo_space, V8.MemoryExternalFragmentationLoSpace)   \
-  /* Percentages of heap committed to each space. */                           \
-  HP(heap_fraction_new_space, V8.MemoryHeapFractionNewSpace)                   \
-  HP(heap_fraction_old_space, V8.MemoryHeapFractionOldSpace)                   \
-  HP(heap_fraction_code_space, V8.MemoryHeapFractionCodeSpace)                 \
-  HP(heap_fraction_map_space, V8.MemoryHeapFractionMapSpace)                   \
-  HP(heap_fraction_lo_space, V8.MemoryHeapFractionLoSpace)
+  HP(external_fragmentation_lo_space, V8.MemoryExternalFragmentationLoSpace)
 
 // Note: These use Histogram with options (min=1000, max=500000, buckets=50).
 #define HISTOGRAM_LEGACY_MEMORY_LIST(HM)                                      \

src/heap/heap.cc

@@ -889,18 +889,6 @@ void Heap::GarbageCollectionEpilogue() {
     isolate_->counters()->external_fragmentation_total()->AddSample(
         static_cast<int>(100 - (SizeOfObjects() * 100.0) / CommittedMemory()));
 
-    isolate_->counters()->heap_fraction_new_space()->AddSample(static_cast<int>(
-        (new_space()->CommittedMemory() * 100.0) / CommittedMemory()));
-    isolate_->counters()->heap_fraction_old_space()->AddSample(static_cast<int>(
-        (old_space()->CommittedMemory() * 100.0) / CommittedMemory()));
-    isolate_->counters()->heap_fraction_code_space()->AddSample(
-        static_cast<int>((code_space()->CommittedMemory() * 100.0) /
-                         CommittedMemory()));
-    isolate_->counters()->heap_fraction_map_space()->AddSample(static_cast<int>(
-        (map_space()->CommittedMemory() * 100.0) / CommittedMemory()));
-    isolate_->counters()->heap_fraction_lo_space()->AddSample(static_cast<int>(
-        (lo_space()->CommittedMemory() * 100.0) / CommittedMemory()));
-
     isolate_->counters()->heap_sample_total_committed()->AddSample(
         static_cast<int>(CommittedMemory() / KB));
     isolate_->counters()->heap_sample_total_used()->AddSample(