cc: Add image to rect map in DiscardableImageMap.

cc/playback/display_item_list.h

Index: cc/playback/display_item_list.h
diff --git a/cc/playback/display_item_list.h b/cc/playback/display_item_list.h
index fcfccd9faf1ba0bf8ade13b7998eb547189d87df..d2b194c3dd6830eeb4e20f0076be9145b1b98dcc 100644
--- a/cc/playback/display_item_list.h
+++ b/cc/playback/display_item_list.h
@@ -19,6 +19,7 @@
 #include "cc/base/rtree.h"
 #include "cc/playback/discardable_image_map.h"
 #include "cc/playback/display_item.h"
+#include "cc/playback/image_id.h"
 #include "third_party/skia/include/core/SkPicture.h"
 #include "ui/gfx/color_space.h"
 #include "ui/gfx/geometry/rect.h"
@@ -149,6 +150,7 @@ class CC_EXPORT DisplayItemList
   void GetDiscardableImagesInRect(const gfx::Rect& rect,
                                   float contents_scale,
                                   std::vector<DrawImage>* images);
+  gfx::Rect GetRectForImage(ImageId image_id) const;
 
   void SetRetainVisualRectsForTesting(bool retain) {
     retain_visual_rects_ = retain;