Prepare for move-only PassOwnPtr in the remaining directories.

third_party/WebKit/Source/platform/graphics/CompositorMutatorClient.cpp

 // Copyright 2016 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 "platform/graphics/CompositorMutatorClient.h"
 
 #include "base/bind.h"
 #include "base/callback.h"
 #include "platform/TraceEvent.h"
 #include "platform/graphics/CompositorMutation.h"
@@ skipping 19 matching lines @@
     if (!m_mutations)
         return base::Closure();
 
     return base::Bind(&CompositorMutationsTarget::applyMutations,
         base::Unretained(m_mutationsTarget),
         base::Owned(m_mutations.release().leakPtr()));
 }
 
 void CompositorMutatorClient::setMutationsForTesting(PassOwnPtr<CompositorMutations> mutations)
 {
-    m_mutations = mutations;
+    m_mutations = std::move(mutations);
 }
 
 } // namespace blink