content: Add public context creation API.

content/public/browser/android/compositor.h

 // Copyright (c) 2012 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 CONTENT_PUBLIC_BROWSER_ANDROID_COMPOSITOR_H_
 #define CONTENT_PUBLIC_BROWSER_ANDROID_COMPOSITOR_H_
 
 #include "base/callback.h"
 #include "cc/resources/ui_resource_bitmap.h"
 #include "content/common/content_export.h"
 #include "ui/android/resources/ui_resource_provider.h"
 #include "ui/gfx/geometry/rect.h"
 #include "ui/gfx/geometry/size.h"
 #include "ui/gfx/native_widget_types.h"
 
 namespace cc {
 class Layer;
 }
 
 namespace ui {
 class ResourceManager;
 class UIResourceProvider;
 }
 
+namespace gpu {
+class GpuChannelEstablishFactory;
+}
+
 namespace content {
 class CompositorClient;
 
 // An interface to the browser-side compositor.
 class CONTENT_EXPORT Compositor {
  public:
   virtual ~Compositor() {}
 
   // Performs the global initialization needed before any compositor
   // instance can be used. This should be called only once.
   static void Initialize();
 
+  static gpu::GpuChannelEstablishFactory* GetGpuChannelFactory();

[klausw, 2017/03/05 01:49:54]

Should this get a brief comment how it should or should not be used? For
example, it's probably not a good idea to use this context for drawing to the
same surface the compositor is trying to use.

[Khushal, 2017/03/05 01:59:53]

Added a comment. And I think its in general understood that when the compositor
is provided with a surface, no one else should be drawing to it.

+
   // Creates and returns a compositor instance.  |root_window| needs to outlive
   // the compositor as it manages callbacks on the compositor.
   static Compositor* Create(CompositorClient* client,
                             gfx::NativeWindow root_window);
 
   // Attaches the layer tree.
   virtual void SetRootLayer(scoped_refptr<cc::Layer> root) = 0;
 
   // Set the output surface bounds.
   virtual void SetWindowBounds(const gfx::Size& size) = 0;
@@ skipping 14 matching lines @@
   // Returns the resource manager associated with the compositor.
   virtual ui::ResourceManager& GetResourceManager() = 0;
 
  protected:
   Compositor() {}
 };
 
 }  // namespace content
 
 #endif  // CONTENT_PUBLIC_BROWSER_ANDROID_COMPOSITOR_H_