Add TRACE_EVENT_IS_NEW_TRACE as a way to snapshot objects at start of recording

cc/resources/picture.h

 // Copyright 2012 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 CC_RESOURCES_PICTURE_H_
 #define CC_RESOURCES_PICTURE_H_
 
 #include <string>
 #include <utility>
 #include <vector>
@@ skipping 94 matching lines @@
     const Picture* picture_;
     const PixelRefs* current_pixel_refs_;
     unsigned current_index_;
 
     gfx::Point min_point_;
     gfx::Point max_point_;
     int current_x_;
     int current_y_;
   };
 
+  void EmitTraceSnapshot();
+
  private:
   explicit Picture(gfx::Rect layer_rect);
   Picture(const base::Value*, bool* success);
   // This constructor assumes SkPicture is already ref'd and transfers
   // ownership to this picture.
   Picture(const skia::RefPtr<SkPicture>&,
           gfx::Rect layer_rect,
           gfx::Rect opaque_rect,
           const PixelRefMap& pixel_refs);
   ~Picture();
@@ skipping 14 matching lines @@
     AsTraceableRasterData(gfx::Rect rect, float scale);
 
   friend class base::RefCountedThreadSafe<Picture>;
   friend class PixelRefIterator;
   DISALLOW_COPY_AND_ASSIGN(Picture);
 };
 
 }  // namespace cc
 
 #endif  // CC_RESOURCES_PICTURE_H_