Remove external begin frame source parameter and settings

cc/trees/proxy_main.h

 // Copyright 2015 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_TREES_PROXY_MAIN_H_
 #define CC_TREES_PROXY_MAIN_H_
 
 #include "base/macros.h"
 #include "cc/base/cc_export.h"
 #include "cc/input/top_controls_state.h"
@@ skipping 75 matching lines @@
   void SetNeedsAnimate() override;
   void SetNeedsUpdateLayers() override;
   void SetNeedsCommit() override;
   void SetNeedsRedraw(const gfx::Rect& damage_rect) override;
   void SetNextCommitWaitsForActivation() override;
   void NotifyInputThrottledUntilCommit() override;
   void SetDeferCommits(bool defer_commits) override;
   bool CommitRequested() const override;
   bool BeginMainFrameRequested() const override;
   void MainThreadHasStoppedFlinging() override;
-  void Start(
-      std::unique_ptr<BeginFrameSource> external_begin_frame_source) override;
+  void Start() override;
   void Stop() override;
   bool SupportsImplScrolling() const override;
   void SetMutator(std::unique_ptr<LayerTreeMutator> mutator) override;
   bool MainFrameWillHappenForTesting() override;
   void ReleaseCompositorFrameSink() override;
   void UpdateTopControlsState(TopControlsState constraints,
                               TopControlsState current,
                               bool animate) override;
 
   // This sets the channel used by ProxyMain to communicate with ProxyImpl.
@@ skipping 30 matching lines @@
   bool defer_commits_;
 
   std::unique_ptr<ChannelMain> channel_main_;
 
   DISALLOW_COPY_AND_ASSIGN(ProxyMain);
 };
 
 }  // namespace cc
 
 #endif  // CC_TREES_PROXY_MAIN_H_