[Mac] Give page actions a default image when preview enabled.

chrome/browser/cocoa/location_bar/page_action_decoration.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/page_action_decoration.h"
 
 #include "base/sys_string_conversions.h"
 #import "chrome/browser/cocoa/extensions/extension_action_context_menu.h"
 #import "chrome/browser/cocoa/extensions/extension_popup_controller.h"
 #import "chrome/browser/cocoa/location_bar/location_bar_view_mac.h"
@@ skipping 123 matching lines @@
       else
         icon_path = page_action_->default_icon_path();
 
       if (!icon_path.empty()) {
         PageActionMap::iterator iter = page_action_icons_.find(icon_path);
         if (iter != page_action_icons_.end())
           skia_icon = iter->second;
       }
     }
 
-    if (!skia_icon.isNull())
+    if (!skia_icon.isNull()) {
       SetImage(gfx::SkBitmapToNSImage(skia_icon));
+    } else if (!GetImage()) {
+      // During install the action can be displayed before the icons
+      // have come in.  Rather than deal with this in multiple places,
+      // provide a placeholder image.  This will be replaced when an
+      // icon comes in.
+      const NSSize default_size = NSMakeSize(Extension::kPageActionIconMaxSize,
+                                             Extension::kPageActionIconMaxSize);
+      SetImage([[NSImage alloc] initWithSize:default_size]);
+    }
   }
   if (IsVisible() != visible) {
     SetVisible(visible);
     NotificationService::current()->Notify(
         NotificationType::EXTENSION_PAGE_ACTION_VISIBILITY_CHANGED,
         Source<ExtensionAction>(page_action_),
         Details<TabContents>(contents));
   }
 }
 
@@ skipping 41 matching lines @@
       if (popup && ![popup isClosing])
         [popup close];
 
       break;
     }
     default:
       NOTREACHED() << "Unexpected notification";
       break;
   }
 }