Ensure that a browser action is never passed to a function which expects a page action.

chrome/browser/cocoa/location_bar/location_bar_view_mac.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/location_bar/location_bar_view_mac.h"
 
 #include "app/l10n_util_mac.h"
 #include "app/resource_bundle.h"
 #include "base/nsimage_cache_mac.h"
 #include "base/stl_util-inl.h"
@@ skipping 269 matching lines @@
   return browser_->GetSelectedTabContents();
 }
 
 PageActionDecoration* LocationBarViewMac::GetPageActionDecoration(
     ExtensionAction* page_action) {
   DCHECK(page_action);
   for (size_t i = 0; i < page_action_decorations_.size(); ++i) {
     if (page_action_decorations_[i]->page_action() == page_action)
       return page_action_decorations_[i];
   }
+  // If |page_action| is the browser action of an extension, no element in
+  // |page_action_decorations_| will match.
   NOTREACHED();
   return NULL;
 }
 
 void LocationBarViewMac::SetPreviewEnabledPageAction(
     ExtensionAction* page_action, bool preview_enabled) {
   DCHECK(page_action);
   TabContents* contents = GetTabContents();
   if (!contents)
     return;
@@ skipping 254 matching lines @@
 
   // These need to change anytime the layout changes.
   // TODO(shess): Anytime the field editor might have changed, the
   // cursor rects almost certainly should have changed.  The tooltips
   // might change even when the rects don't change.
   [field_ resetFieldEditorFrameIfNeeded];
   [field_ updateCursorAndToolTipRects];
 
   [field_ setNeedsDisplay:YES];
 }