cc: Build Image to Region map during image meta-data generation.

cc/playback/discardable_image_map.h

Index: cc/playback/discardable_image_map.h
diff --git a/cc/playback/discardable_image_map.h b/cc/playback/discardable_image_map.h
index adae86248074cf55fec472076a52369a56fe49b0..b0eaa63fd2c8a7fdcd1b1efeae08ce22bb09863f 100644
--- a/cc/playback/discardable_image_map.h
+++ b/cc/playback/discardable_image_map.h
@@ -5,10 +5,12 @@
 #ifndef CC_PLAYBACK_DISCARDABLE_IMAGE_MAP_H_
 #define CC_PLAYBACK_DISCARDABLE_IMAGE_MAP_H_
 
+#include <unordered_map>
 #include <utility>
 #include <vector>
 
 #include "cc/base/cc_export.h"
+#include "cc/base/region.h"
 #include "cc/base/rtree.h"
 #include "cc/playback/draw_image.h"
 #include "third_party/skia/include/core/SkCanvas.h"
@@ -18,6 +20,9 @@
 
 namespace cc {
 
+// A map of SkImage id to the region for this image.
+using ImageToRegionMap = std::unordered_map<uint32_t, Region>;

[vmpstr, 2016/11/15 18:57:54]

Can you put this as a member of DiscardableImageMap?

[Khushal, 2016/11/16 05:01:58]

Done.

+
 // Helper function to apply the matrix to the rect and return the result.
 SkRect MapRect(const SkMatrix& matrix, const SkRect& src);
 
@@ -46,6 +51,7 @@ class CC_EXPORT DiscardableImageMap {
   void GetDiscardableImagesInRect(const gfx::Rect& rect,
                                   const gfx::SizeF& raster_scales,
                                   std::vector<DrawImage>* images) const;
+  Region GetRegionForImage(const SkImage* image) const;
 
  private:
   friend class ScopedMetadataGenerator;
@@ -55,6 +61,8 @@ class CC_EXPORT DiscardableImageMap {
   void EndGeneratingMetadata();
 
   std::vector<std::pair<DrawImage, gfx::Rect>> all_images_;
+  ImageToRegionMap image_to_region_;

[vmpstr, 2016/11/15 18:57:54]

nit: image_id_to_region_map_

[Khushal, 2016/11/16 05:01:58]

Done.

+
   RTree images_rtree_;
 };