Add flag to disable impl-side painting

cc/util.cc

+// Copyright 2012 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 "base/command_line.h"
+#include "cc/switches.h"
+
+namespace cc {
+
+bool IsImplSidePaintingEnabled(const CommandLine *cl)
+{
+    // The disable flag takes precedence over the enable flag.
+    if (cl->HasSwitch(cc::switches::kDisableImplSidePainting))
+        return false;
+
+    return cl->HasSwitch(cc::switches::kEnableImplSidePainting);
+}
+
+}  // namespace cc