Remove explicit keyword from multi-argument constructors

chrome/browser/ui/gtk/bubble/bubble_gtk.h

 // Copyright (c) 2011 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 CHROME_BROWSER_UI_GTK_BUBBLE_BUBBLE_GTK_H_
 #define CHROME_BROWSER_UI_GTK_BUBBLE_BUBBLE_GTK_H_
 #pragma once
 
 #include <gtk/gtk.h>
 
@@ skipping 79 matching lines @@
   // that the content's widgets will appear inactive even after the user clicks
   // in them.
   void HandlePointerAndKeyboardUngrabbedByContent();
 
  private:
   enum FrameType {
     FRAME_MASK,
     FRAME_STROKE,
   };
 
-  explicit BubbleGtk(GtkThemeService* provider, bool match_system_theme);
+  BubbleGtk(GtkThemeService* provider, bool match_system_theme);
   virtual ~BubbleGtk();
 
   // Creates the Bubble.
   void Init(GtkWidget* anchor_widget,
             const gfx::Rect* rect,
             GtkWidget* content,
             ArrowLocationGtk arrow_location,
             bool grab_input);
 
   // Make the points for our polygon frame, either for fill (the mask), or for
@@ skipping 96 matching lines @@
   bool closed_by_escape_;
 
   NotificationRegistrar registrar_;
 
   ui::GtkSignalRegistrar signals_;
 
   DISALLOW_COPY_AND_ASSIGN(BubbleGtk);
 };
 
 #endif  // CHROME_BROWSER_UI_GTK_BUBBLE_BUBBLE_GTK_H_