[tracing] Don't register tracing-related allocations.

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 ae5f73af432bc9ecfb4aa87c8734238176490fe3..4f2a8c95026ac611350763ea4df674f8bd60c743 100644
--- a/base/trace_event/heap_profiler_allocation_context_tracker.h
+++ b/base/trace_event/heap_profiler_allocation_context_tracker.h
@@ -70,8 +70,8 @@ class BASE_EXPORT AllocationContextTracker {
   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.
+  // ignored by the heap profiler. GetContextSnapshot() returns false when
+  // allocations are ignored.
   void begin_ignore_scope() { ignore_scope_depth_++; }
   void end_ignore_scope() {
     if (ignore_scope_depth_)
@@ -89,8 +89,9 @@ class BASE_EXPORT AllocationContextTracker {
   void PushCurrentTaskContext(const char* context);
   void PopCurrentTaskContext(const char* context);
 
-  // Returns a snapshot of the current thread-local context.
-  AllocationContext GetContextSnapshot();
+  // Fills a snapshot of the current thread-local context. Doesn't fill and
+  // returns false if allocations are being ignored.
+  bool GetContextSnapshot(AllocationContext* snapshot);
 
   ~AllocationContextTracker();