[tracing] Ignore tracing allocations in heap profiler

base/trace_event/heap_profiler_allocation_context_tracker.h

Index: base/trace_event/heap_profiler_allocation_context_tracker.h
diff --git a/base/trace_event/heap_profiler_allocation_context_tracker.h b/base/trace_event/heap_profiler_allocation_context_tracker.h
index e5c8c187739b99afaa0f75995b1a534dd14a2e4d..632a4eface8740a9415337c41c6d9874fb107367 100644
--- a/base/trace_event/heap_profiler_allocation_context_tracker.h
+++ b/base/trace_event/heap_profiler_allocation_context_tracker.h
@@ -52,6 +52,15 @@ class BASE_EXPORT AllocationContextTracker {
   // if capture is enabled.
   static void SetCurrentThreadName(const char* name);
 
+  // Starts and ends a new ignore scope between which the allocations are
+  // ignored in the heap profiler. A dummy context that short circuits to
+  // "tracing_overhead" is returned for these allocations.
+  void begin_ignore_scope() { ignore_scope_depth_++; }
+  void end_ignore_scope() {
+    if (ignore_scope_depth_)
+      ignore_scope_depth_--;
+  }
+
   // Pushes a frame onto the thread-local pseudo stack.
   void PushPseudoStackFrame(const char* trace_event_name);
 
@@ -83,6 +92,8 @@ class BASE_EXPORT AllocationContextTracker {
   // pseudo stack to cluster allocations.
   std::vector<const char*> task_contexts_;
 
+  uint32_t ignore_scope_depth_;
+
   DISALLOW_COPY_AND_ASSIGN(AllocationContextTracker);
 };