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

content/renderer/browser_plugin/mock_browser_plugin_manager.h

 // 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.
 
 #ifndef CONTENT_RENDERER_BROWSER_PLUGIN_MOCK_BROWSER_PLUGIN_MANAGER_H_
 #define CONTENT_RENDERER_BROWSER_PLUGIN_MOCK_BROWSER_PLUGIN_MANAGER_H_
 
 #include "content/renderer/browser_plugin/browser_plugin_manager.h"
 
 #include "base/memory/scoped_ptr.h"
 #include "ipc/ipc_message_utils.h"
 #include "ipc/ipc_test_sink.h"
 
 namespace content {
 
 class MockBrowserPluginManager : public BrowserPluginManager {
  public:
-  MockBrowserPluginManager(RenderViewImpl* render_view);
+  explicit MockBrowserPluginManager(RenderViewImpl* render_view);
 
   // BrowserPluginManager implementation.
   virtual BrowserPlugin* CreateBrowserPlugin(
       RenderViewImpl* render_view,
       WebKit::WebFrame* frame,
       const WebKit::WebPluginParams& params) OVERRIDE;
 
   // Provides access to the messages that have been received by this thread.
   IPC::TestSink& sink() { return sink_; }
 
   // RenderViewObserver override.
   virtual bool OnMessageReceived(const IPC::Message& message) OVERRIDE;
   virtual bool Send(IPC::Message* msg) OVERRIDE;
  protected:
   virtual ~MockBrowserPluginManager();
   IPC::TestSink sink_;
 
   // The last known good deserializer for sync messages.
   scoped_ptr<IPC::MessageReplyDeserializer> reply_deserializer_;
 
   DISALLOW_COPY_AND_ASSIGN(MockBrowserPluginManager);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_RENDERER_BROWSER_PLUGIN_MOCK_BROWSER_PLUGIN_MANAGER_H_