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

chrome/browser/ui/cocoa/panels/panel_cocoa.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.
 
 #include "chrome/browser/ui/cocoa/panels/panel_cocoa.h"
 
 #include "base/logging.h"
 #import "chrome/browser/ui/cocoa/chrome_event_processing_window.h"
 #import "chrome/browser/ui/cocoa/panels/panel_titlebar_view_cocoa.h"
 #import "chrome/browser/ui/cocoa/panels/panel_utils_cocoa.h"
@@ skipping 264 matching lines @@
 
 void PanelCocoa::DidCloseNativeWindow() {
   DCHECK(!isClosed());
   panel_->OnNativePanelClosed();
   controller_ = NULL;
 }
 
 // NativePanelTesting implementation.
 class CocoaNativePanelTesting : public NativePanelTesting {
  public:
-  CocoaNativePanelTesting(NativePanel* native_panel);
+  explicit CocoaNativePanelTesting(NativePanel* native_panel);
   virtual ~CocoaNativePanelTesting() { }
   // Overridden from NativePanelTesting
   virtual void PressLeftMouseButtonTitlebar(
       const gfx::Point& mouse_location, panel::ClickModifier modifier) OVERRIDE;
   virtual void ReleaseMouseButtonTitlebar(
       panel::ClickModifier modifier) OVERRIDE;
   virtual void DragTitlebar(const gfx::Point& mouse_location) OVERRIDE;
   virtual void CancelDragTitlebar() OVERRIDE;
   virtual void FinishDragTitlebar() OVERRIDE;
   virtual bool VerifyDrawingAttention() const OVERRIDE;
@@ skipping 86 matching lines @@
       return ![[titlebar() closeButton] isHidden];
     case panel::MINIMIZE_BUTTON:
       return ![[titlebar() minimizeButton] isHidden];
     case panel::RESTORE_BUTTON:
       return ![[titlebar() restoreButton] isHidden];
     default:
       NOTREACHED();
   }
   return false;
 }