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

chrome/browser/ui/cocoa/gradient_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/cocoa_test_helper.h"
 #import "chrome/browser/ui/cocoa/gradient_button_cell.h"
+#import "chrome/browser/ui/cocoa/test/cocoa_test_helper.h"
 #include "testing/gtest/include/gtest/gtest.h"
 #include "testing/platform_test.h"
 #import "ui/events/test/cocoa_test_event_utils.h"
 
 @interface GradientButtonCell (HoverValueTesting)
 - (void)performOnePulseStep;
 @end
 
 namespace {
 
@@ skipping 91 matching lines @@
 }
 
 // Test drawing when first responder, mostly to ensure nothing leaks or
 // crashes.
 TEST_F(GradientButtonCellTest, FirstResponder) {
   [test_window() makePretendKeyWindowAndSetFirstResponder:view_];
   [view_ display];
 }
 
 }  // namespace