Swap main menu with app-specific menu when app window focused.

chrome/browser/ui/cocoa/apps/app_menu_controller_mac.mm

+// Copyright 2013 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 "chrome/browser/ui/cocoa/apps/app_menu_controller_mac.h"
+
+#include "apps/app_shim/extension_app_shim_handler_mac.h"
+#include "apps/shell_window.h"
+#include "apps/shell_window_registry.h"
+#include "base/strings/sys_string_conversions.h"
+#import "chrome/browser/ui/cocoa/apps/native_app_window_cocoa.h"
+#include "chrome/common/extensions/extension.h"
+#include "ui/base/l10n/l10n_util.h"
+#include "ui/base/l10n/l10n_util_mac.h"
+
+@interface AppMenuController ()
+// Construct the NSMenuItems for apps.
+- (void)buildAppMenuItems;
+// Register for NSWindow notifications.
+- (void)registerEventHandlers;
+// If the window is an app window, add or remove menu items.
+- (void)windowMainStatusChanged:(NSNotification*)notification;
+// Add menu items for an app and hide Chrome menu items.
+- (void)addMenuItems:(const extensions::Extension*)app;
+// If the window belongs to the currently focused app, remove the menu items and
+// unhide Chrome menu items.
+- (void)removeMenuItems:(NSString*)appId;
+@end
+
+@implementation AppMenuController
+
+- (id)init {
+  if ((self = [super init])) {
+    [self buildAppMenuItems];
+    [self registerEventHandlers];
+  }
+  return self;
+}
+
+- (void)buildAppMenuItems {
+  appMenuItem_.reset([[NSMenuItem alloc] initWithTitle:@""
+                                                action:nil
+                                         keyEquivalent:@""]);
+  base::scoped_nsobject<NSMenu> appMenu([[NSMenu alloc] initWithTitle:@""]);
+  [appMenuItem_ setSubmenu:appMenu];
+}
+
+- (void)registerEventHandlers {
+  [[NSNotificationCenter defaultCenter]
+      addObserver:self
+         selector:@selector(windowMainStatusChanged:)
+             name:NSWindowDidBecomeMainNotification
+           object:nil];
+
+  [[NSNotificationCenter defaultCenter]
+      addObserver:self
+         selector:@selector(windowMainStatusChanged:)
+             name:NSWindowDidResignMainNotification
+           object:nil];
+
+  [[NSNotificationCenter defaultCenter]
+      addObserver:self
+         selector:@selector(windowMainStatusChanged:)
+             name:NSWindowWillCloseNotification
+           object:nil];
+}
+
+- (void)unregisterEventHandlers {
+  [[NSNotificationCenter defaultCenter] removeObserver:self];
+}
+
+- (void)windowMainStatusChanged:(NSNotification*)notification {
+  id window = [notification object];
+  id windowController = [window windowController];
+  if (![windowController isKindOfClass:[NativeAppWindowController class]])
+    return;
+
+  apps::ShellWindow* shellWindow =
+      apps::ShellWindowRegistry::GetShellWindowForNativeWindowAnyProfile(
+          window);
+  if (!shellWindow)
+    return;
+
+  if ([notification name] == NSWindowDidBecomeMainNotification) {
+    [self addMenuItems:shellWindow->extension()];
+  } else if ([notification name] == NSWindowDidResignMainNotification ||
+             [notification name] == NSWindowWillCloseNotification) {
+    [self removeMenuItems:base::SysUTF8ToNSString(shellWindow->extension_id())];
+  } else {
+    NOTREACHED();
+  }
+}
+
+- (void)addMenuItems:(const extensions::Extension*)app {
+  NSString* appId = base::SysUTF8ToNSString(app->id());
+  NSString* title = base::SysUTF8ToNSString(app->name());
+
+  if ([appId_ isEqualToString:appId])
+    return;
+
+  [self removeMenuItems:appId_];
+  appId_.reset([appId retain]);
+
+  NSMenu* mainMenu = [NSApp mainMenu];
+  for (NSMenuItem* item in [mainMenu itemArray])
+    [item setHidden:YES];
+
+  [appMenuItem_ setTitle:appId];
+  [[appMenuItem_ submenu] setTitle:title];
+  [mainMenu addItem:appMenuItem_];
+}
+
+- (void)removeMenuItems:(NSString*)appId {
+  if (![appId_ isEqualToString:appId])
+    return;
+
+  appId_.reset();
+
+  NSMenu* mainMenu = [NSApp mainMenu];
+  [mainMenu removeItem:appMenuItem_];
+
+  // Restore the Chrome main menu bar.
+  for (NSMenuItem* item in [mainMenu itemArray])
+    [item setHidden:NO];
+}
+
+@end