Update the nine patch layer to use UI resources

cc/resources/ui_resource.h

Index: cc/resources/ui_resource.h
diff --git a/cc/resources/ui_resource.h b/cc/resources/ui_resource.h
new file mode 100644
index 0000000000000000000000000000000000000000..f399544751c644b8f55fc7bae42a0ec6b3f103b4
--- /dev/null
+++ b/cc/resources/ui_resource.h
@@ -0,0 +1,24 @@
+// Copyright 2013 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 CC_RESOURCES_UI_RESOURCE_H_
+#define CC_RESOURCES_UI_RESOURCE_H_
+
+#include "base/memory/ref_counted.h"
+#include "cc/base/cc_export.h"
+#include "cc/resources/ui_resource_bitmap.h"
+#include "cc/resources/ui_resource_client.h"
+#include "ui/gfx/size.h"
+
+namespace cc {
+
+class CC_EXPORT UIResource {
+ public:
+  virtual UIResourceId id() = 0;
+  virtual gfx::Size GetSize() = 0;

[aelias_OOO_until_Jul13, 2013/08/22 04:55:52]

Could we instead add a GetUIResourceSize(UIResourceID id) method to
LayerTreeHost and get rid of both these new UIResource and SharedUIResource
classes?

[powei, 2013/08/22 17:58:47]

I added this function.  But we might need to keep around these two classes for
now  because of the reason mentioned in the SetBitmap comment.

[aelias_OOO_until_Jul13, 2013/08/27 18:40:49]

I think we should delete UIResource and SharedUIResource, they're entirely
redundant abstractions.  If it needs a Blink patch to adjust the interface on
that end then so be it.

[powei, 2013/08/27 19:04:57]

Yes, I agree they seem to be redundant classes.   I will delete them.  But would
you object to me moving some of these abstraction to private classes within
NinePatchLayer?  

My main goal in creating these two classes is to have a single resource variable
(resource_) in NinePatchLayer for two resource-attaching interfaces (SetBitmap &
SetSharedBitmap) instead of introducing more logic to keep around both a
UIResourceId and a ScopedUIResource.  

[aelias_OOO_until_Jul13, 2013/08/27 19:07:23]

Yeah, it's probably more acceptable as a private class.

+};
+
+}  // namespace cc
+
+#endif  // CC_RESOURCES_UI_RESOURCE_H_