ozone: gbm: Add overlay support

ui/ozone/public/surface_ozone_egl.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 UI_OZONE_PUBLIC_SURFACE_OZONE_EGL_H_
 #define UI_OZONE_PUBLIC_SURFACE_OZONE_EGL_H_
 
 #include "base/basictypes.h"
 #include "base/memory/scoped_ptr.h"
 #include "ui/ozone/ozone_base_export.h"
@@ skipping 33 matching lines @@
   // InitializeHardware. Returns an empty scoped_ptr on error.
   virtual scoped_ptr<gfx::VSyncProvider> CreateVSyncProvider() = 0;
 
   // Sets the overlay plane to switch to at the next page flip.
   // |plane_z_order| specifies the stacking order of the plane relative to the
   // main framebuffer located at index 0.
   // |plane_transform| specifies how the buffer is to be transformed during.
   // composition.
   // |buffer| to be presented by the overlay.
   // |display_bounds| specify where it is supposed to be on the screen.
-  // |crop_rect| specifies the region within the buffer to be placed inside
-  // |display_bounds|.
+  // |crop_rect| specifies the region within the buffer to be placed
+  // inside |display_bounds|. This is specified in texture coordinates, in the
+  // range of [0,1].
   virtual bool ScheduleOverlayPlane(int plane_z_order,
                                     gfx::OverlayTransform plane_transform,
                                     scoped_refptr<NativePixmap> buffer,
                                     const gfx::Rect& display_bounds,
                                     const gfx::RectF& crop_rect) = 0;
 };
 
 }  // namespace ui
 
 #endif  // UI_OZONE_PUBLIC_SURFACE_OZONE_EGL_H_