[MacViews] Use ChromeCommandDispatcherDelegate to handle keyboard shortcuts.

chrome/browser/ui/cocoa/chrome_command_dispatcher_delegate.mm

Index: chrome/browser/ui/cocoa/chrome_command_dispatcher_delegate.mm
diff --git a/chrome/browser/ui/cocoa/chrome_command_dispatcher_delegate.mm b/chrome/browser/ui/cocoa/chrome_command_dispatcher_delegate.mm
index 3d0bf8fc024f1e74e9d3764a2ab182fcebea8a4a..6d3cd88777924595c3554a6767da7a36d40e2e66 100644
--- a/chrome/browser/ui/cocoa/chrome_command_dispatcher_delegate.mm
+++ b/chrome/browser/ui/cocoa/chrome_command_dispatcher_delegate.mm
@@ -79,6 +79,8 @@ bool HandleExtraBrowserKeyboardShortcut(NSEvent* event, NSWindow* window) {
   // redispatched event, [event window] gives the correct window.
   if ([event window]) {
     BrowserWindowController* controller = [[event window] windowController];
+    // |controller| is only set in Cocoa. In toolkit-views extension commands
+    // are handled by BrowserView.
     if ([controller respondsToSelector:@selector(handledByExtensionCommand:
                                                                   priority:)]) {
       ui::AcceleratorManager::HandlerPriority priority =