Split ThreadProxy methods to ProxyMain and ProxyImpl.

cc/trees/proxy_common.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_COMMON_H_
+#define CC_TREES_PROXY_COMMON_H_
+
+#include "cc/base/cc_export.h"
+#include "cc/output/begin_frame_args.h"
+#include "cc/trees/layer_tree_host_common.h"
+
+namespace cc {
+class LayerTreeHost;
+
+struct CC_EXPORT BeginMainFrameAndCommitState {
+  BeginMainFrameAndCommitState();
+  ~BeginMainFrameAndCommitState();
+
+  unsigned int begin_frame_id;
+  BeginFrameArgs begin_frame_args;
+  scoped_ptr<ScrollAndScaleSet> scroll_info;
+  size_t memory_allocation_limit_bytes;
+  bool evicted_ui_resources;
+};
+
+struct CC_EXPORT BlockedMainCommitState {

[Khushal, 2015/10/17 02:02:48]

This is basically to simulate some form of message passing in the threaded case
of the channel. It would be great if ProxyImpl didn't hold on to a pointer to
the LTH. Since it sees the actual state of the LayerTree only during the commit.

I would prefer it if we could something like,

channel_main->StartCommitOnImpl(LayerTreeHost* layer_tree_host, bool*
hold_commit_for_activation);

Channel holds on to the pointer or proto.

channel_impl->FinishCommitToLayerTreeHostImpl(LayerTreeHostImpl* host_impl )
In this method, we finish the commit with
LTH->FinishCommitOnImplThread(host_impl) and clear the
hold_commit_for_activation flag.
I would just pass the flag value and clear it when starting the commit, but the
startcommitonimpl in ProxyImpl can abort the call if there is no LTHI and the
flag remains uncleared then.

+  BlockedMainCommitState();
+  ~BlockedMainCommitState();
+
+  LayerTreeHost* layer_tree_host;
+  bool* commit_waits_for_activation;
+};
+
+}  // namespace cc
+
+#endif  // CC_TREES_PROXY_COMMON_H_