Makes ImageView do a bit more checking before assuming images equal

ui/views/controls/image_view.h

Index: ui/views/controls/image_view.h
diff --git a/ui/views/controls/image_view.h b/ui/views/controls/image_view.h
index 18c4ba13241ac01afe2d2604b3e361350dd32de5..5ca63dd54bdb2458c9e59c14de8e17bf8b867fbe 100644
--- a/ui/views/controls/image_view.h
+++ b/ui/views/controls/image_view.h
@@ -84,6 +84,11 @@ class VIEWS_EXPORT ImageView : public View {
   virtual bool HitTestRect(const gfx::Rect& rect) const OVERRIDE;
 
  private:
+  // Returns true if |img| is the same as the last image we painted. This is
+  // intended to be a quick check, not exhaustive. In other words it's possible
+  // this may return false even though the images are in fact equal.

[pkotwicz, 2013/11/15 20:57:09]

Nit: "this may return false" -> "that this returns false"

[sky, 2013/11/15 22:19:13]

Done.

+  bool IsImageEqual(const gfx::ImageSkia& img) const;
+
   // Compute the image origin given the desired size and the receiver alignment
   // properties.
   gfx::Point ComputeImageOrigin(const gfx::Size& image_size) const;
@@ -109,6 +114,13 @@ class VIEWS_EXPORT ImageView : public View {
   // A flag controlling hit test handling for interactivity.
   bool interactive_;
 
+  // Scale last painted at.
+  float last_paint_scale_;
+
+  // Address of bytes we last painted. This is used only for comparison, so its
+  // safe to cache.
+  void* last_painted_image_;

[pkotwicz, 2013/11/15 20:57:09]

Maybe |last_painted_bitmap_| I try to reserve the "image" keyword for gfx::Image
and gfx::ImageSkia

[sky, 2013/11/15 22:19:13]

I went with last_painted_bitmap_pixels_

+
   DISALLOW_COPY_AND_ASSIGN(ImageView);
 };