Make sure manifest specified shortcut for Extension Command can not override the built-in shortcuts.

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

 // 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/browser/ui/cocoa/extensions/extension_keybinding_registry_cocoa.h"
 
 #include "chrome/browser/extensions/api/commands/command_service.h"
 #include "chrome/browser/extensions/extension_service.h"
 #include "chrome/browser/profiles/profile.h"
+#include "chrome/browser/ui/cocoa/accelerators_cocoa.h"
 #include "chrome/common/extensions/extension.h"
 #include "chrome/common/chrome_notification_types.h"
 #include "chrome/common/extensions/extension_manifest_constants.h"
 #include "content/public/browser/native_web_keyboard_event.h"
 #include "content/public/browser/notification_service.h"
+#include "ui/base/accelerators/platform_accelerator_cocoa.h"
+#include "ui/base/keycodes/keyboard_code_conversion_mac.h"
 
 namespace values = extension_manifest_values;
 
 // static
 void extensions::ExtensionKeybindingRegistry::SetShortcutHandlingSuspended(
     bool suspended) {
   ExtensionKeybindingRegistryCocoa::set_shortcut_handling_suspended(suspended);
 }
 
+// static
+bool extensions::ExtensionKeybindingRegistry::IsChromeAccelerator(

[Nico, 2013/04/09 16:10:18]

Is this supposed to return true if a shortcut is used anywhere in the UI? If so,
this isn't correct: Most of chrome/mac shortcuts are defined in MainMenu.xib,
AcceleratorsCocoa just lists a few common alternative shortcuts. I think there's
code to get all shortcuts that are listed in the menu somewhere though.
(chrome/browser/ui/cocoa/nsmenuitem_additions.h , cr_firesForKeyEvent: is
probably a good place to start looking

+    const ui::Accelerator& accelerator) {
+  // The |accelerator| passed in contains a Windows key code but no platform
+  // accelerator info. The Accelerator list is the opposite: It has accelerators
+  // that have key_code() == VKEY_UNKNOWN but they contain a platform
+  // accelerator. We find common ground by converting the passed in Windows key
+  // code to a character and use that when comparing against the Accelerator
+  // list.
+  unichar character;
+  unichar characterIgnoringModifiers;
+  ui::MacKeyCodeForWindowsKeyCode(accelerator.key_code(),
+                                  0,
+                                  &character,
+                                  &characterIgnoringModifiers);
+  NSString* characters =
+      [[[NSString alloc] initWithCharacters:&character length:1] autorelease];
+
+  NSUInteger modifiers =
+      (accelerator.IsCtrlDown() ? NSControlKeyMask : 0) |
+      (accelerator.IsCmdDown() ? NSCommandKeyMask : 0) |
+      (accelerator.IsAltDown() ? NSAlternateKeyMask : 0) |
+      (accelerator.IsShiftDown() ? NSShiftKeyMask : 0);
+
+  AcceleratorsCocoa* accelerators = AcceleratorsCocoa::GetInstance();
+  for (AcceleratorsCocoa::const_iterator iter = accelerators->begin();
+       iter != accelerators->end(); ++iter) {
+    const ui::PlatformAcceleratorCocoa* platform_accelerator =
+        static_cast<const ui::PlatformAcceleratorCocoa*>(
+            iter->second.platform_accelerator());
+    if ([characters isEqualToString:platform_accelerator->characters()] &&
+        modifiers == platform_accelerator->modifier_mask())
+      return true;
+  }
+  return false;
+}
+
 bool ExtensionKeybindingRegistryCocoa::shortcut_handling_suspended_ = false;
 
 ExtensionKeybindingRegistryCocoa::ExtensionKeybindingRegistryCocoa(
     Profile* profile,
     gfx::NativeWindow window,
     ExtensionFilter extension_filter,
     Delegate* delegate)
     : ExtensionKeybindingRegistry(profile, extension_filter, delegate),
       profile_(profile),
       window_(window) {
@@ skipping 105 matching lines @@
     const extensions::Extension* extension,
     const std::string& command_name) {
   EventTargets::iterator iter = event_targets_.begin();
   while (iter != event_targets_.end()) {
     EventTargets::iterator old = iter++;
     if (old->second.first == extension->id() &&
         (command_name.empty() || (old->second.second == command_name)))
       event_targets_.erase(old);
   }
 }