Add missing (and remove superfluous) 'explicit' from constructors.

content/browser/renderer_host/media/audio_renderer_host_unittest.cc

 // Copyright (c) 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/bind.h"
 #include "base/environment.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/message_loop.h"
 #include "base/process_util.h"
 #include "base/sync_socket.h"
@@ skipping 23 matching lines @@
 
 static bool IsRunningHeadless() {
   scoped_ptr<base::Environment> env(base::Environment::Create());
   if (env->HasVar("CHROME_HEADLESS"))
     return true;
   return false;
 }
 
 class MockAudioRendererHost : public AudioRendererHost {
  public:
-  explicit MockAudioRendererHost(
+  MockAudioRendererHost(
       media::AudioManager* audio_manager,
       MediaObserver* media_observer)
       : AudioRendererHost(audio_manager, media_observer),
         shared_memory_length_(0) {
   }
 
   // A list of mock methods.
   MOCK_METHOD2(OnStreamCreated,
                void(int stream_id, int length));
   MOCK_METHOD1(OnStreamPlaying, void(int stream_id));
@@ skipping 337 matching lines @@
 
   Create();
   Play();
   SimulateError();
   Close();
 }
 
 // TODO(hclam): Add tests for data conversation in low latency mode.
 
 }  // namespace content