Split ThreadProxy methods to ProxyMain and ProxyImpl.

cc/trees/proxy_common.cc

+// 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.
+
+#include "cc/trees/proxy_common.h"
+#include "cc/trees/layer_tree_host.h"
+
+namespace cc {
+
+BeginMainFrameAndCommitState::BeginMainFrameAndCommitState()
+    : memory_allocation_limit_bytes(0), evicted_ui_resources(false) {}
+
+BeginMainFrameAndCommitState::~BeginMainFrameAndCommitState() {}
+
+BlockedMainCommitState::BlockedMainCommitState()
+    : layer_tree_host(nullptr), commit_waits_for_activation(nullptr) {}
+
+BlockedMainCommitState::~BlockedMainCommitState() {}
+
+}  // namespace cc