views: Mark single-argument constructors as explicit.

ui/views/examples/bubble_example.cc

-// Copyright (c) 2011 The Chromium Authors. All rights reserved.
+// 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 "ui/views/examples/bubble_example.h"
 
 #include "base/utf_string_conversions.h"
 #include "ui/views/bubble/bubble_delegate.h"
 #include "ui/views/controls/button/text_button.h"
 #include "ui/views/controls/label.h"
 #include "ui/views/layout/box_layout.h"
@@ skipping 18 matching lines @@
                               BubbleBorder::NONE, false, false };
 BubbleConfig kArrowConfig = { ASCIIToUTF16("Arrow"), SK_ColorGRAY, NULL,
                               BubbleBorder::TOP_LEFT, false, false };
 BubbleConfig kFadeInConfig = { ASCIIToUTF16("FadeIn"), SK_ColorYELLOW, NULL,
                                BubbleBorder::BOTTOM_RIGHT, true, false };
 BubbleConfig kFadeOutConfig = { ASCIIToUTF16("FadeOut"), SK_ColorWHITE, NULL,
                                 BubbleBorder::LEFT_TOP, false, true };
 
 class ExampleBubbleDelegateView : public BubbleDelegateView {
  public:
-  ExampleBubbleDelegateView(const BubbleConfig& config)
+  explicit ExampleBubbleDelegateView(const BubbleConfig& config)
       : BubbleDelegateView(config.anchor_view, config.arrow),
         label_(config.label) {
     set_color(config.color);
   }
 
  protected:
   virtual void Init() OVERRIDE {
     SetLayoutManager(new FillLayout());
     Label* label = new Label(label_);
     AddChildView(label);
@@ skipping 42 matching lines @@
     bubble_delegate->Show();
 
   if (config.fade_out) {
     bubble_delegate->set_close_on_esc(false);
     bubble_delegate->StartFade(false);
   }
 }
 
 }  // namespace examples
 }  // namespace views