Refactor away the Browser* dependency in exclusive_access

chrome/test/base/test_browser_window.cc

 // 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.
 
 #include "chrome/test/base/test_browser_window.h"
 
 #include "chrome/browser/ui/browser_list.h"
 #include "chrome/browser/ui/browser_list_observer.h"
 #include "ui/gfx/geometry/rect.h"
 
@@ skipping 213 matching lines @@
 }
 
 int
 TestBrowserWindow::GetRenderViewHeightInsetWithDetachedBookmarkBar() {
   return 0;
 }
 
 void TestBrowserWindow::ExecuteExtensionCommand(
     const extensions::Extension* extension,
     const extensions::Command& command) {}
+
+ExclusiveAccessContext* TestBrowserWindow::GetExclusiveAccessContext() {
+  return nullptr;
+}