Disable collection backing reallocation during pre finalizer

third_party/WebKit/Source/platform/heap/ThreadState.cpp

Index: third_party/WebKit/Source/platform/heap/ThreadState.cpp
diff --git a/third_party/WebKit/Source/platform/heap/ThreadState.cpp b/third_party/WebKit/Source/platform/heap/ThreadState.cpp
index f090ee923ecfa4f9044f98d399921767c794ac6c..8eab252005c7e79bf7d4b77f94608cbc455a0d9d 100644
--- a/third_party/WebKit/Source/platform/heap/ThreadState.cpp
+++ b/third_party/WebKit/Source/platform/heap/ThreadState.cpp
@@ -110,6 +110,7 @@ ThreadState::ThreadState()
       gc_forbidden_count_(0),
       mixins_being_constructed_count_(0),
       accumulated_sweeping_time_(0),
+      no_backing_reallocation_(false),
       vector_backing_arena_index_(BlinkGC::kVector1ArenaIndex),
       current_arena_ages_(0),
       gc_mixin_marker_(nullptr),
@@ -1267,6 +1268,7 @@ void ThreadState::InvokePreFinalizers() {
   TRACE_EVENT0("blink_gc", "ThreadState::invokePreFinalizers");
 
   SweepForbiddenScope sweep_forbidden(this);
+  NoBackingReallocationScope no_backing_reallocation(this);

[kouhei (in TOK), 2017/04/12 06:14:01]

How about just using platform/wtf/AutoReset.h?

[haraken, 2017/04/12 06:44:34]

I'd prefer using a scope since ThreadState is already using a bunch of scopes.

You also need to add the scope to the weak processing.

Nit: Move the scope to below ScriptForbiddenIfMainThreadScope.
SweepForbiddenScope and ScriptForbiddenIfMainThreadScope should be coupled.

[keishi, 2017/04/12 09:43:53]

Weak processing is already in the NoAllocationScope. Since I reused
Allocator::isAllocationAllowed, we don't need to add
ObjectResurrectionForbiddenScope. Should I still add it.

   ScriptForbiddenIfMainThreadScope script_forbidden;
 
   double start_time = WTF::CurrentTimeMS();