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

athena/activity/public/activity_view_model.h

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef ATHENA_ACTIVITY_PUBLIC_ACTIVITY_VIEW_MODEL_H_
 #define ATHENA_ACTIVITY_PUBLIC_ACTIVITY_VIEW_MODEL_H_
 
 #include "athena/athena_export.h"
 #include "base/strings/string16.h"
 
 typedef unsigned int SkColor;
 
 namespace gfx {
+class Image;
 class ImageSkia;
 }
 
 namespace views {
 class View;
 class Widget;
 }
 
 namespace athena {
 
@@ skipping 27 matching lines @@
   virtual views::View* GetContentsView() = 0;
 
   // Creates a custom widget for the activity. Returns NULL to use default
   // implementation.
   virtual views::Widget* CreateWidget() = 0;
 
   // Returns an image which can be used to represent the activity in e.g. the
   // 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;
 
   // Undoes any changes done by PrepareContentsForOverview().
   virtual void ResetContentsView() = 0;
 };
 
 }  // namespace athena
 
 #endif  // ATHENA_ACTIVITY_PUBLIC_ACTIVITY_VIEW_MODEL_H_