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

content/renderer/browser_plugin/browser_plugin_manager_impl.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_BROWSER_PLUGIN_MANAGER_IMPL_H_
 #define CONTENT_RENDERER_BROWSER_PLUGIN_BROWSER_PLUGIN_MANAGER_IMPL_H_
 
 #include "content/renderer/browser_plugin/browser_plugin_manager.h"
 #include "googleurl/src/gurl.h"
 
 struct BrowserPluginMsg_UpdateRect_Params;
 class WebCursor;
 
 namespace gfx {
 class Point;
 }
 
 namespace content {
 
 class BrowserPluginManagerImpl : public BrowserPluginManager {
  public:
-  BrowserPluginManagerImpl(RenderViewImpl* render_view);
+  explicit BrowserPluginManagerImpl(RenderViewImpl* render_view);
 
   // BrowserPluginManager implementation.
   virtual BrowserPlugin* CreateBrowserPlugin(
       RenderViewImpl* render_view,
       WebKit::WebFrame* frame,
       const WebKit::WebPluginParams& params) OVERRIDE;
 
   // IPC::Sender implementation.
   virtual bool Send(IPC::Message* msg) OVERRIDE;
 
   // RenderViewObserver override. Call on render thread.
   virtual bool OnMessageReceived(const IPC::Message& message) OVERRIDE;
  private:
   virtual ~BrowserPluginManagerImpl();
 
   void OnPluginAtPositionRequest(const IPC::Message& message,
                                  int request_id,
                                  const gfx::Point& position);
 
   // Returns whether a message should be forwarded to BrowserPlugins.
   static bool ShouldForwardToBrowserPlugin(const IPC::Message& message);
 
   DISALLOW_COPY_AND_ASSIGN(BrowserPluginManagerImpl);
 };
 
 }  // namespace content
 
 #endif //  CONTENT_RENDERER_BROWSER_PLUGIN_BROWSER_PLUGIN_MANAGER_IMPL_H_