Create c/b/ui/cocoa/test and move test files to there

chrome/browser/ui/cocoa/clickhold_button_cell_unittest.mm

 // 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.
 
 #import <Cocoa/Cocoa.h>
 
 #include "base/mac/scoped_nsobject.h"
 #import "chrome/browser/ui/cocoa/clickhold_button_cell.h"
-#import "chrome/browser/ui/cocoa/cocoa_test_helper.h"
+#import "chrome/browser/ui/cocoa/test/cocoa_test_helper.h"
 #include "testing/gtest/include/gtest/gtest.h"
 #include "testing/gtest_mac.h"
 #include "testing/platform_test.h"
 
 @interface ClickHoldButtonCellTestTarget : NSObject {
  @private
   BOOL didOpen_;
 }
 - (void)open;
 - (BOOL)didOpen;
@@ skipping 105 matching lines @@
   [cell setEnableRightClick:YES];
 
   actionNames = [cell accessibilityActionNames];
   EXPECT_TRUE([actionNames containsObject:NSAccessibilityShowMenuAction]);
 
   [cell accessibilityPerformAction:NSAccessibilityShowMenuAction];
   EXPECT_TRUE([cellTarget didOpen]);
 }
 
 }  // namespace