[wrapper-tracing] Cache wrapper tracing status in ThreadState

Bug: 
Change-Id: I23ad4603ce6dcc8934827e0cfbef0f8427afe5ad
Reviewed-on: https://chromium-review.googlesource.com/600189
Commit-Queue: Michael Lippautz <mlippautz@chromium.org>
Reviewed-by: Kentaro Hara <haraken@chromium.org>
Cr-Commit-Position: refs/heads/master@{#491830}

third_party/WebKit/Source/platform/bindings/ScriptWrappableVisitor.cpp

@@ -37,6 +37,7 @@ void ScriptWrappableVisitor::TracePrologue() {
   CHECK(marking_deque_.IsEmpty());
   CHECK(verifier_deque_.IsEmpty());
   tracing_in_progress_ = true;
+  ThreadState::Current()->SetWrapperTracingInProgress(true);
 }
 
 void ScriptWrappableVisitor::EnterFinalPause() {
@@ -58,6 +59,7 @@ void ScriptWrappableVisitor::TraceEpilogue() {
 
   should_cleanup_ = true;
   tracing_in_progress_ = false;
+  ThreadState::Current()->SetWrapperTracingInProgress(false);
   ScheduleIdleLazyCleanup();
 }
 
@@ -65,6 +67,7 @@ void ScriptWrappableVisitor::AbortTracing() {
   CHECK(ThreadState::Current());
   should_cleanup_ = true;
   tracing_in_progress_ = false;
+  ThreadState::Current()->SetWrapperTracingInProgress(false);
   PerformCleanup();
 }
 
@@ -223,7 +226,8 @@ void ScriptWrappableVisitor::WriteBarrier(
     v8::Isolate* isolate,
     const void* src_object,
     const TraceWrapperV8Reference<v8::Value>* dst_object) {
-  if (!src_object || !dst_object || dst_object->IsEmpty()) {
+  if (!src_object || !dst_object || dst_object->IsEmpty() ||
+      !ThreadState::Current()->WrapperTracingInProgress()) {
     return;
   }
   // We only require a write barrier if |srcObject|  is already marked. Note
@@ -239,7 +243,8 @@ void ScriptWrappableVisitor::WriteBarrier(
 void ScriptWrappableVisitor::WriteBarrier(
     v8::Isolate* isolate,
     const v8::Persistent<v8::Object>* dst_object) {
-  if (!dst_object || dst_object->IsEmpty()) {
+  if (!dst_object || dst_object->IsEmpty() ||
+      !ThreadState::Current()->WrapperTracingInProgress()) {
     return;
   }
   CurrentVisitor(isolate)->MarkWrapper(&(dst_object->As<v8::Value>()));

third_party/WebKit/Source/platform/bindings/ScriptWrappableVisitor.h

@@ -117,6 +117,13 @@ class PLATFORM_EXPORT ScriptWrappableVisitor : public v8::EmbedderHeapTracer,
     if (!src_object || !dst_object) {
       return;
     }
+
+    const ThreadState* thread_state = ThreadState::Current();
+    DCHECK(thread_state);
+    // Bail out if tracing is not in progress.
+    if (!thread_state->WrapperTracingInProgress())
+      return;
+
     // We only require a write barrier if |srcObject|  is already marked. Note
     // that this implicitly disables the write barrier when the GC is not
     // active as object will not be marked in this case.
@@ -124,8 +131,6 @@ class PLATFORM_EXPORT ScriptWrappableVisitor : public v8::EmbedderHeapTracer,
       return;
     }
 
-    const ThreadState* thread_state = ThreadState::Current();
-    DCHECK(thread_state);
     // If the wrapper is already marked we can bail out here.
     if (TraceTrait<T>::GetHeapObjectHeader(dst_object)->IsWrapperHeaderMarked())
       return;

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

@@ -123,6 +123,8 @@ ThreadState::ThreadState()
       isolate_(nullptr),
       trace_dom_wrappers_(nullptr),
       invalidate_dead_objects_in_wrappers_marking_deque_(nullptr),
+      perform_cleanup_(nullptr),
+      wrapper_tracing_in_progress_(false),
 #if defined(ADDRESS_SANITIZER)
       asan_fake_stack_(__asan_get_current_fake_stack()),
 #endif

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

@@ -292,6 +292,11 @@ class PLATFORM_EXPORT ThreadState {
     object_resurrection_forbidden_ = false;
   }
 
+  bool WrapperTracingInProgress() const { return wrapper_tracing_in_progress_; }
+  void SetWrapperTracingInProgress(bool value) {
+    wrapper_tracing_in_progress_ = value;
+  }
+
   class MainThreadGCForbiddenScope final {
     STACK_ALLOCATED();
 
@@ -679,6 +684,7 @@ class PLATFORM_EXPORT ThreadState {
   void (*trace_dom_wrappers_)(v8::Isolate*, Visitor*);
   void (*invalidate_dead_objects_in_wrappers_marking_deque_)(v8::Isolate*);
   void (*perform_cleanup_)(v8::Isolate*);
+  bool wrapper_tracing_in_progress_;
 
 #if defined(ADDRESS_SANITIZER)
   void* asan_fake_stack_;