Make RenderViewImpl::OnForceRedraw more robust

cc/trees/swap_promise_monitor.h

 // Copyright 2013 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_SWAP_PROMISE_MONITOR_H_
 #define CC_TREES_SWAP_PROMISE_MONITOR_H_
 
 #include "cc/base/cc_export.h"
 
 namespace cc {
@@ skipping 14 matching lines @@
  public:
   // If the monitor lives on the main thread, pass in layer_tree_host
   // and set layer_tree_host_impl to nullptr.
   // If the monitor lives on the impl thread, pass in layer_tree_host_impl
   // and set layer_tree_host to nullptr.
   SwapPromiseMonitor(LayerTreeHost* layer_tree_host,
                      LayerTreeHostImpl* layer_tree_host_impl);
   virtual ~SwapPromiseMonitor();
 
   virtual void OnSetNeedsCommitOnMain() = 0;
+  virtual void OnSetNeedsForcedRedrawOnMain() = 0;

[piman, 2016/07/28 20:54:09]

Is this and the associated logic in LTH really needed? It looks like the same
logic (RenderViewImpl::OnForceRedraw) both creates the concrete swap promise
monitor and forces redraw. Couldn't it directly tell the monitor that it forces
redraw, instead of going through LTH to do that?

   virtual void OnSetNeedsRedrawOnImpl() = 0;
   virtual void OnForwardScrollUpdateToMainThreadOnImpl() = 0;
 
  protected:
   LayerTreeHost* layer_tree_host_;
   LayerTreeHostImpl* layer_tree_host_impl_;
 };
 
 }  // namespace cc
 
 #endif  // CC_TREES_SWAP_PROMISE_MONITOR_H_