Implement frame attribution (FrameBlamer)

content/renderer/top_level_blame_context.h

+// Copyright 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef CONTENT_RENDERER_TOP_LEVEL_BLAME_CONTEXT_H_
+#define CONTENT_RENDERER_TOP_LEVEL_BLAME_CONTEXT_H_
+
+#include "base/trace_event/blame_context.h"
+
+namespace content {
+
+// A blame context which spans all the frames in this renderer. Used for
+// attributing work which cannot be associated with a specific frame (e.g.,
+// garbage collection).
+class TopLevelBlameContext : public base::trace_event::BlameContext {
+ public:
+  TopLevelBlameContext();
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(TopLevelBlameContext);
+};
+
+}  // namespace content
+
+#endif  // CONTENT_RENDERER_TOP_LEVEL_BLAME_CONTEXT_H_