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

chrome/browser/ui/cocoa/tabs/throbbing_image_view.mm

 // 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.
 
 #import "chrome/browser/ui/cocoa/tabs/throbbing_image_view.h"
 
 #include "ui/base/animation/animation_delegate.h"
 
 class ThrobbingImageViewAnimationDelegate : public ui::AnimationDelegate {
  public:
-  ThrobbingImageViewAnimationDelegate(NSView* view) : view_(view) {}
+  explicit ThrobbingImageViewAnimationDelegate(NSView* view) : view_(view) {}
   virtual void AnimationProgressed(const ui::Animation* animation) OVERRIDE {
     [view_ setNeedsDisplay:YES];
   }
  private:
   NSView* view_;  // weak
 };
 
 @implementation ThrobbingImageView
 
 - (id)initWithFrame:(NSRect)rect
@@ skipping 22 matching lines @@
                       fromRect:NSZeroRect
                      operation:NSCompositeSourceOver
                       fraction:1];
   [throbImage_ drawInRect:[self bounds]
                  fromRect:NSZeroRect
                 operation:NSCompositeSourceOver
                  fraction:throbAnimation_->GetCurrentValue()];
 }
 
 @end