Implement frame attribution (FrameBlamer)

third_party/WebKit/Source/bindings/core/v8/V8GCController.cpp

Index: third_party/WebKit/Source/bindings/core/v8/V8GCController.cpp
diff --git a/third_party/WebKit/Source/bindings/core/v8/V8GCController.cpp b/third_party/WebKit/Source/bindings/core/v8/V8GCController.cpp
index 7fb4f48543c9c0dbd414bc9fa0eda454aadfe0e7..48cb24bd1536d3fd51735379a0422234d2bd731b 100644
--- a/third_party/WebKit/Source/bindings/core/v8/V8GCController.cpp
+++ b/third_party/WebKit/Source/bindings/core/v8/V8GCController.cpp
@@ -51,6 +51,7 @@
 #include "core/svg/SVGElement.h"
 #include "platform/Histogram.h"
 #include "platform/TraceEvent.h"
+#include "public/platform/WebBlameContext.h"
 #include "wtf/Partitions.h"
 #include "wtf/Vector.h"
 #include <algorithm>
@@ -275,8 +276,14 @@ void gcPrologueForMajorGC(v8::Isolate* isolate, bool constructRetainedObjectInfo
 
 void V8GCController::gcPrologue(v8::Isolate* isolate, v8::GCType type, v8::GCCallbackFlags flags)
 {
-    if (isMainThread())
+    if (isMainThread()) {
         ScriptForbiddenScope::enter();
+        // Attribute garbage collection to the entire thread instead of a specific
+        // frame.
+    }
+
+    if (WebBlameContext* blame_context = Platform::current()->threadBlameContext())
+        blame_context->enter();
 
     // TODO(haraken): A GC callback is not allowed to re-enter V8. This means
     // that it's unsafe to run Oilpan's GC in the GC callback because it may
@@ -284,7 +291,6 @@ void V8GCController::gcPrologue(v8::Isolate* isolate, v8::GCType type, v8::GCCal
     // a task to schedule the Oilpan's GC.
     // (In practice, there is no finalizer that calls into V8 and thus is safe.)
 
-    v8::HandleScope scope(isolate);
     switch (type) {
     case v8::kGCTypeScavenge:
         if (ThreadState::current())
@@ -339,8 +345,12 @@ void V8GCController::gcEpilogue(v8::Isolate* isolate, v8::GCType type, v8::GCCal
         ASSERT_NOT_REACHED();
     }
 
-    if (isMainThread())
+    if (isMainThread()) {
         ScriptForbiddenScope::exit();
+    }
+
+    if (WebBlameContext* blame_context = Platform::current()->threadBlameContext())
+        blame_context->leave();
 
     // v8::kGCCallbackFlagForced forces a Blink heap garbage collection
     // when a garbage collection was forced from V8. This is either used