Refactor: Untangle Mac's ExclusiveAccessContext from BrowserWindow

chrome/browser/ui/exclusive_access/exclusive_access_context.cc

 // Copyright (c) 2015 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/exclusive_access/exclusive_access_context.h"
 
 #include "base/logging.h"
 #include "build/build_config.h"
 
+// This file provides default implementations for the ExclusiveAccessContext
+// methods that only some platforms care about.
+
 bool ExclusiveAccessContext::SupportsFullscreenWithToolbar() const {
   return false;
 }
 
 void ExclusiveAccessContext::UpdateFullscreenWithToolbar(bool with_toolbar) {
   NOTIMPLEMENTED();
 }
 
 void ExclusiveAccessContext::ToggleFullscreenToolbar() {
   NOTIMPLEMENTED();
 }
 
+bool ExclusiveAccessContext::IsFullscreenWithToolbar() const {
+  return false;
+}
+
 #if defined(OS_WIN)
 void ExclusiveAccessContext::SetMetroSnapMode(bool enable) {
   NOTIMPLEMENTED();
 }
 
 bool ExclusiveAccessContext::IsInMetroSnapMode() const {
   return false;
 }
 #endif  // defined(OS_WIN)
-
-void ExclusiveAccessContext::UnhideDownloadShelf() {
-  // NOOP implementation.
-}
-
-void ExclusiveAccessContext::HideDownloadShelf() {
-  // NOOP implementation.
-}