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

chrome/browser/ui/cocoa/history_menu_bridge_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 <vector>
 
 #include "base/memory/ref_counted_memory.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/string_util.h"
 #include "base/sys_string_conversions.h"
 #include "base/utf_string_conversions.h"
 #include "chrome/app/chrome_command_ids.h"
 #include "chrome/browser/common/cancelable_request.h"
 #include "chrome/browser/sessions/persistent_tab_restore_service.h"
 #include "chrome/browser/sessions/session_types_test_helper.h"
 #include "chrome/browser/ui/cocoa/cocoa_profile_test.h"
 #include "chrome/browser/ui/cocoa/history_menu_bridge.h"
 #include "testing/gmock/include/gmock/gmock.h"
 #include "testing/gtest/include/gtest/gtest.h"
 #import "testing/gtest_mac.h"
 #include "third_party/skia/include/core/SkBitmap.h"
 #include "ui/gfx/codec/png_codec.h"
 
 namespace {
 
 class MockTRS : public PersistentTabRestoreService {
  public:
-  MockTRS(Profile* profile) : PersistentTabRestoreService(profile, NULL) {}
+  explicit MockTRS(Profile* profile)
+      : PersistentTabRestoreService(profile, NULL) {}
   MOCK_CONST_METHOD0(entries, const TabRestoreService::Entries&());
 };
 
 class MockBridge : public HistoryMenuBridge {
  public:
-  MockBridge(Profile* profile)
+  explicit MockBridge(Profile* profile)
       : HistoryMenuBridge(profile),
         menu_([[NSMenu alloc] initWithTitle:@"History"]) {}
 
   virtual NSMenu* HistoryMenu() {
     return menu_.get();
   }
 
  private:
   scoped_nsobject<NSMenu> menu_;
 };
@@ skipping 308 matching lines @@
   image_result.image = gfx::Image(bitmap);
   GotFaviconData(&item, image_result);
 
   // Make sure the callback works.
   EXPECT_FALSE(item.icon_requested);
   EXPECT_TRUE(item.icon.get());
   EXPECT_TRUE([item.menu_item image]);
 }
 
 }  // namespace