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

Index: chrome/browser/ui/cocoa/extensions/extension_keybinding_registry_cocoa.mm
diff --git a/chrome/browser/ui/cocoa/extensions/extension_keybinding_registry_cocoa.mm b/chrome/browser/ui/cocoa/extensions/extension_keybinding_registry_cocoa.mm
index 1ee3c0f652ff0796967cc7d8273d8dac7a7211e2..5fd34033a6ce4d159fbcd516c288c713c033ee87 100644
--- a/chrome/browser/ui/cocoa/extensions/extension_keybinding_registry_cocoa.mm
+++ b/chrome/browser/ui/cocoa/extensions/extension_keybinding_registry_cocoa.mm
@@ -7,11 +7,15 @@
 #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"
+#import "chrome/browser/ui/cocoa/browser_window_utils.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;
 
@@ -21,6 +25,60 @@ void extensions::ExtensionKeybindingRegistry::SetShortcutHandlingSuspended(
   ExtensionKeybindingRegistryCocoa::set_shortcut_handling_suspended(suspended);
 }
 
+// static
+bool extensions::ExtensionKeybindingRegistry::IsChromeAccelerator(
+    const ui::Accelerator& accelerator, Profile* profile) {
+  // 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);
+
+  NSEvent* event = [NSEvent keyEventWithType:NSKeyDown
+                                    location:NSZeroPoint
+                               modifierFlags:modifiers
+                                   timestamp:0
+                                windowNumber:0
+                                     context:nil
+                                  characters:characters
+                 charactersIgnoringModifiers:characters
+                                   isARepeat:NO
+                                     keyCode:accelerator.key_code()];
+
+  content::NativeWebKeyboardEvent keyboard_event(event);
+  int id = [BrowserWindowUtils getCommandId:keyboard_event];
+  if (id != -1)
+    return true;
+
+  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(