Improve GL helpers.

mojo/gpu/gl_context.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 MOJO_GPU_GL_CONTEXT_H_
 #define MOJO_GPU_GL_CONTEXT_H_
 
 #include "base/basictypes.h"
 #include "base/memory/weak_ptr.h"
 #include "base/observer_list.h"
 #include "mojo/public/c/gpu/MGL/mgl.h"
 #include "mojo/public/cpp/bindings/interface_ptr.h"
 
 namespace mojo {
+class ApplicationConnector;
 class CommandBuffer;
 using CommandBufferPtr = InterfacePtr<CommandBuffer>;
 class Shell;
 
 class GLContext {
  public:
   class Observer {
    public:
     virtual void OnContextLost() = 0;
 
    protected:
     virtual ~Observer();
   };
 
-  static base::WeakPtr<GLContext> Create(Shell* shell);
+  // Creates an offscreen GL context.
+  static base::WeakPtr<GLContext> CreateOffscreen(
+      ApplicationConnector* connector);
+
+  // Creates a GL context from a command buffer.
   static base::WeakPtr<GLContext> CreateFromCommandBuffer(
       CommandBufferPtr command_buffer);
 
   void MakeCurrent();
   bool IsCurrent();
   void Destroy();
 
   void AddObserver(Observer* observer);
   void RemoveObserver(Observer* observer);
 
  private:
   explicit GLContext(CommandBufferPtr command_buffer);
   ~GLContext();
 
   static void ContextLostThunk(void* self);
   void OnContextLost();
 
   MGLContext context_;
 
   base::ObserverList<Observer> observers_;
   base::WeakPtrFactory<GLContext> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(GLContext);
 };
 
 }  // namespace mojo
 
 #endif  // MOJO_GPU_GL_CONTEXT_H_