Add end to end test for Media galleries scan API.

chrome/browser/ui/cocoa/extensions/media_galleries_scan_result_dialog_cocoa.mm

 // Copyright 2014 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.
 
 #include "chrome/browser/ui/cocoa/extensions/media_galleries_scan_result_dialog_cocoa.h"
 
 #include "base/mac/foundation_util.h"
 #include "base/mac/scoped_nsobject.h"
 #include "base/strings/sys_string_conversions.h"
 #include "chrome/browser/ui/chrome_style.h"
@@ skipping 173 matching lines @@
     [scroll_view setFrame:scroll_frame];
   }
 
   [main_container_ setFrame:NSMakeRect(
       0, 0, kCheckboxMaxWidth, NSHeight(scroll_frame))];
   [alert_ setAccessoryView:main_container_];
 
   [alert_ layout];
 }
 
+void MediaGalleriesScanResultDialogCocoa::AcceptDialogForTesting() {
+  OnAcceptClicked();
+}
+
 CGFloat MediaGalleriesScanResultDialogCocoa::CreateCheckboxes(
     CGFloat y_pos,
     const MediaGalleriesScanResultDialogController::OrderedScanResults&
         scan_results) {
   y_pos += kCheckboxMargin;
 
   for (MediaGalleriesScanResultDialogController::OrderedScanResults::
        const_iterator iter = scan_results.begin();
        iter != scan_results.end(); iter++) {
     const MediaGalleriesScanResultDialogController::ScanResult& scan_result =
@@ skipping 151 matching lines @@
   return controller_->GetContextMenu(prefid);
 }
 
 // static
 MediaGalleriesScanResultDialog* MediaGalleriesScanResultDialog::Create(
     MediaGalleriesScanResultDialogController* controller) {
   base::scoped_nsobject<MediaGalleriesScanResultCocoaController>
       cocoa_controller([[MediaGalleriesScanResultCocoaController alloc] init]);
   return new MediaGalleriesScanResultDialogCocoa(controller, cocoa_controller);
 }