Remove "mixin" from BeginFrameSource/Observer base classes.

content/browser/android/in_process/synchronous_compositor_external_begin_frame_source.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 CONTENT_BROWSER_ANDROID_IN_PROCESS_SYNCHRONOUS_COMPOSITOR_EXTERNAL_BEGIN_FRAME_SOURCE_H_
 #define CONTENT_BROWSER_ANDROID_IN_PROCESS_SYNCHRONOUS_COMPOSITOR_EXTERNAL_BEGIN_FRAME_SOURCE_H_
 
 #include "base/basictypes.h"
 #include "base/compiler_specific.h"
 #include "cc/scheduler/begin_frame_source.h"
 
 namespace content {
 class SynchronousCompositorImpl;
 
 // Make sure that this is initialized and set to compositor before output
 // surface is bound to compositor.
 class SynchronousCompositorExternalBeginFrameSource
-    : public cc::BeginFrameSourceMixIn {
+    : public cc::BeginFrameSourceBase {
  public:
   explicit SynchronousCompositorExternalBeginFrameSource(int routing_id);
   ~SynchronousCompositorExternalBeginFrameSource() override;
 
   void BeginFrame(const cc::BeginFrameArgs& args);
   void SetCompositor(SynchronousCompositorImpl* compositor);
 
-  // cc::BeginFrameSourceMixIn implementation.
+  // cc::BeginFrameSourceBase implementation.
   void OnNeedsBeginFramesChange(bool needs_begin_frames) override;
   void SetClientReady() override;
 
  private:
   bool CalledOnValidThread() const;
 
   const int routing_id_;
   bool registered_;
 
   // Not owned. This can be null when compositor is gone first than BFS.
   SynchronousCompositorImpl* compositor_;
 
   DISALLOW_COPY_AND_ASSIGN(SynchronousCompositorExternalBeginFrameSource);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_ANDROID_IN_PROCESS_SYNCHRONOUS_COMPOSITOR_EXTERNAL_BEGIN_FRAME_SOURCE_H_