[heap] Report wrappers after processing the marking deque incrementally

BUG=chromium:676700, chromium:468240

Review-Url: https://codereview.chromium.org/2604583002
Cr-Commit-Position: refs/heads/master@{#41946}

src/heap/embedder-tracing.cc

@@ -41,7 +41,7 @@ bool LocalEmbedderHeapTracer::Trace(
     double deadline, EmbedderHeapTracer::AdvanceTracingActions actions) {
   if (!InUse()) return false;
 
-  RegisterWrappersWithRemoteTracer();
+  DCHECK_EQ(0, NumberOfCachedWrappersToTrace());
   return remote_tracer_->AdvanceTracing(deadline, actions);
 }
 

src/heap/incremental-marking.cc

@@ -892,6 +892,11 @@ intptr_t IncrementalMarking::ProcessMarkingDeque(
     VisitObject(map, obj, size);
     bytes_processed += size - unscanned_bytes_of_large_object_;
   }
+  // Report all found wrappers to the embedder. This is necessary as the
+  // embedder could potentially invalidate wrappers as soon as V8 is done
+  // with its incremental marking processing. Any cached wrappers could
+  // result in broken pointers at this point.
+  heap_->local_embedder_heap_tracer()->RegisterWrappersWithRemoteTracer();
   return bytes_processed;
 }
 
@@ -1033,6 +1038,8 @@ double IncrementalMarking::AdvanceIncrementalMarking(
   TRACE_EVENT0("v8", "V8.GCIncrementalMarking");
   TRACE_GC(heap_->tracer(), GCTracer::Scope::MC_INCREMENTAL);
   DCHECK(!IsStopped());
+  DCHECK_EQ(
+      0, heap_->local_embedder_heap_tracer()->NumberOfCachedWrappersToTrace());
 
   double remaining_time_in_ms = 0.0;
   intptr_t step_size_in_bytes = GCIdleTimeHandler::EstimateMarkingStepSize(

src/heap/mark-compact.cc

@@ -2136,6 +2136,7 @@ void MarkCompactCollector::ProcessEphemeralMarking(
     if (!only_process_harmony_weak_collections) {
       if (heap_->local_embedder_heap_tracer()->InUse()) {
         TRACE_GC(heap()->tracer(), GCTracer::Scope::MC_MARK_WRAPPER_TRACING);
+        heap_->local_embedder_heap_tracer()->RegisterWrappersWithRemoteTracer();
         heap_->local_embedder_heap_tracer()->Trace(
             0,
             EmbedderHeapTracer::AdvanceTracingActions(

test/unittests/heap/embedder-tracing-unittest.cc

@@ -135,6 +135,7 @@ TEST(LocalEmbedderHeapTracer, TraceFinishes) {
   local_tracer.AddWrapperToTrace(CreateWrapperInfo());
   EXPECT_EQ(1u, local_tracer.NumberOfCachedWrappersToTrace());
   EXPECT_CALL(remote_tracer, RegisterV8References(_));
+  local_tracer.RegisterWrappersWithRemoteTracer();
   EXPECT_CALL(remote_tracer, AdvanceTracing(0, _)).WillOnce(Return(false));
   EXPECT_FALSE(local_tracer.Trace(
       0, EmbedderHeapTracer::AdvanceTracingActions(
@@ -149,6 +150,7 @@ TEST(LocalEmbedderHeapTracer, TraceDoesNotFinish) {
   local_tracer.AddWrapperToTrace(CreateWrapperInfo());
   EXPECT_EQ(1u, local_tracer.NumberOfCachedWrappersToTrace());
   EXPECT_CALL(remote_tracer, RegisterV8References(_));
+  local_tracer.RegisterWrappersWithRemoteTracer();
   EXPECT_CALL(remote_tracer, AdvanceTracing(0, _)).WillOnce(Return(true));
   EXPECT_TRUE(local_tracer.Trace(
       0, EmbedderHeapTracer::AdvanceTracingActions(