Use high resolution icons where possible for streamlined hosted app icons.

ui/gfx/image/image_family.h

Index: ui/gfx/image/image_family.h
diff --git a/ui/gfx/image/image_family.h b/ui/gfx/image/image_family.h
index 93e005d18d063fd838e5f9ec56c99733c216d8fd..35eae462e482dcdb01dd249c66f1b6ff33f0b384 100644
--- a/ui/gfx/image/image_family.h
+++ b/ui/gfx/image/image_family.h
@@ -106,6 +106,9 @@ class GFX_EXPORT ImageFamily {
   // Determines whether the image family has no images in it.
   bool empty() const { return map_.empty(); }
 
+  // Returns the number of images in the family.
+  size_t size() const { return map_.size(); }
+
   // Removes all images from the family.
   void clear() { return map_.clear(); }