[Mac] Finish up extension infobar UI implementation.

chrome/browser/cocoa/extensions/extension_action_context_menu.mm

 // Copyright (c) 2010 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/cocoa/extensions/extension_action_context_menu.h"
 
 #include "app/l10n_util_mac.h"
 #include "base/sys_string_conversions.h"
 #include "base/task.h"
 #include "chrome/browser/browser_list.h"
@@ skipping 225 matching lines @@
     }
     case kExtensionContextInspect: {
       NSPoint popupPoint;
       BrowserWindowCocoa* window =
           static_cast<BrowserWindowCocoa*>(browser->window());
       LocationBar* locationBar = window->GetLocationBar();
       AutocompleteTextField* field =
           (AutocompleteTextField*)locationBar->location_entry()->
           GetNativeView();
       AutocompleteTextFieldCell* fieldCell = [field autocompleteTextFieldCell];
+      DCHECK(action_);
       NSRect popupRect =
           [fieldCell pageActionFrameForExtensionAction:action_
                                                inFrame:[field bounds]];
       if (!NSEqualRects(popupRect, NSZeroRect)) {
         popupRect = [[field superview] convertRect:popupRect toView:nil];
         popupPoint = popupRect.origin;
         NSRect fieldFrame = [field bounds];
         fieldFrame = [field convertRect:fieldFrame toView:nil];
         popupPoint.x += fieldFrame.origin.x + popupRect.size.width / 2;
       } else {
@@ skipping 13 matching lines @@
                                 devMode:YES];
       break;
     }
     default:
       NOTREACHED();
       break;
   }
 }
 
 - (BOOL)validateMenuItem:(NSMenuItem*)menuItem {
-  if([menuItem isEqualTo: inspectorItem_.get()]) {
-    return (action_->HasPopup(CurrentTabId()));
+  if([menuItem isEqualTo:inspectorItem_.get()]) {
+    return action_ && action_->HasPopup(CurrentTabId());
   }
   return YES;
 }
 
 @end