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

content/public/browser/color_chooser.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_PUBLIC_BROWSER_COLOR_CHOOSER_H_
 #define CONTENT_PUBLIC_BROWSER_COLOR_CHOOSER_H_
 
 #include "third_party/skia/include/core/SkColor.h"
 
 namespace content {
 
 class WebContents;
 
 // Abstraction object for color choosers for each platform.
 class ColorChooser {
  public:
   static ColorChooser* Create(int identifier,
                               WebContents* web_contents,
                               SkColor initial_color);
-  ColorChooser(int identifier) : identifier_(identifier) {}
+  explicit ColorChooser(int identifier) : identifier_(identifier) {}
   virtual ~ColorChooser() {}
 
   // Returns a unique identifier for this chooser.  Identifiers are unique
   // across a renderer process.  This avoids race conditions in synchronizing
   // the browser and renderer processes.  For example, if a renderer closes one
   // chooser and opens another, and simultaneously the user picks a color in the
   // first chooser, the IDs can be used to drop the "chose a color" message
   // rather than erroneously tell the renderer that the user picked a color in
   // the second chooser.
   int identifier() const { return identifier_; }
 
   // Ends connection with color chooser. Closes color chooser depending on the
   // platform.
   virtual void End() = 0;
 
   // Sets the selected color.
   virtual void SetSelectedColor(SkColor color) = 0;
 
 private:
   int identifier_;
 };
 
 }  // namespace content
 
 #endif  // CONTENT_PUBLIC_BROWSER_COLOR_CHOOSER_H_