Creating PNG images from web content to be used by OverviewMode navigation

athena/activity/public/activity_view_model.h

Index: athena/activity/public/activity_view_model.h
diff --git a/athena/activity/public/activity_view_model.h b/athena/activity/public/activity_view_model.h
index 7412af224946908dd9839dbb6584bb9f8cf4d1c9..ecda2f98c919d58e107e8cedca670b60b6f6954e 100644
--- a/athena/activity/public/activity_view_model.h
+++ b/athena/activity/public/activity_view_model.h
@@ -11,6 +11,7 @@
 typedef unsigned int SkColor;
 
 namespace gfx {
+class Image;
 class ImageSkia;
 }
 
@@ -58,8 +59,9 @@ class ATHENA_EXPORT ActivityViewModel {
   // overview mode. The returned image can have no size if either a view exists
   // or the activity has not yet been loaded. In that case
   // GetRepresentativeColor() should be used to clear the preview area.
+  // The ownership gets passed to the caller.

[oshima, 2014/09/24 00:40:01]

gfx::Image shares the internal storage, so this may be a bit misleading. How
about something like "it is guaranteed that the images stored in the returned
gfx::Image will not be modified" ?

[Mr4D (OOO till 08-26), 2014/09/24 16:18:25]

Since the ActivityViewModel does not keep a reference, the receiver will
(implicitly) delete the object when the reference disappears. Okay. Will change
comment.

   // Note: We intentionally do not use a layer / view for this.
-  virtual gfx::ImageSkia GetOverviewModeImage() = 0;
+  virtual gfx::Image GetOverviewModeImage() = 0;

[oshima, 2014/09/24 00:40:01]

I think gfx::ImageSkia is enough. You may land it as is, and I'll look into it.

 
   // Prepares the contents view for overview.
   virtual void PrepareContentsForOverview() = 0;