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

chrome/browser/ui/cocoa/bookmarks/bookmark_bar_controller_unittest.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 <Cocoa/Cocoa.h>
 
 #include "base/basictypes.h"
 #include "base/command_line.h"
 #include "base/memory/scoped_nsobject.h"
 #include "base/string16.h"
@@ skipping 170 matching lines @@
     dragDataNodes.push_back(dragDataNode_);
   }
   return dragDataNodes;
 }
 
 @end
 
 
 class FakeTheme : public ui::ThemeProvider {
  public:
-  FakeTheme(NSColor* color) : color_(color) {}
+  explicit FakeTheme(NSColor* color) : color_(color) {}
   scoped_nsobject<NSColor> color_;
 
   virtual gfx::ImageSkia* GetImageSkiaNamed(int id) const { return NULL; }
   virtual SkColor GetColor(int id) const { return SkColor(); }
   virtual bool GetDisplayProperty(int id, int* result) const { return false; }
   virtual bool ShouldUseNativeFrame() const { return false; }
   virtual bool HasCustomImage(int id) const { return false; }
   virtual base::RefCountedMemory* GetRawData(
       int id,
       ui::ScaleFactor scale_factor) const {
@@ skipping 1966 matching lines @@
                              "2f3b ] 4b ");
   actual = model_test_utils::ModelStringFromNode(root);
   EXPECT_EQ(expected, actual);
 
   // Verify that the other bookmark folder can't be deleted.
   BookmarkButton *otherButton = [bar_ otherBookmarksButton];
   EXPECT_FALSE([bar_ canDragBookmarkButtonToTrash:otherButton]);
 }
 
 }  // namespace