Parse the script_badge manifest section.

chrome/browser/extensions/script_badge_controller.cc

 // Copyright (c) 2012 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.
 
 #include "chrome/browser/extensions/script_badge_controller.h"
 
 #include "chrome/browser/extensions/extension_service.h"
 #include "chrome/browser/extensions/extension_system.h"
 #include "chrome/browser/ui/tab_contents/tab_contents.h"
 #include "chrome/common/extensions/extension.h"
 #include "chrome/common/extensions/extension_action.h"
 #include "chrome/common/extensions/extension_messages.h"
 #include "chrome/common/extensions/extension_set.h"
+#include "chrome/common/extensions/extension_switch_utils.h"
 #include "chrome/common/chrome_notification_types.h"
 #include "content/public/browser/navigation_controller.h"
 #include "content/public/browser/navigation_entry.h"
 #include "content/public/browser/notification_service.h"
 #include "content/public/browser/web_contents.h"
 #include "ipc/ipc_message.h"
 #include "ipc/ipc_message_macros.h"
 
 namespace extensions {
 
 ScriptBadgeController::ScriptBadgeController(TabContents* tab_contents)
     : content::WebContentsObserver(tab_contents->web_contents()),
       script_executor_(tab_contents->web_contents()),
-      tab_contents_(tab_contents) {}
+      tab_contents_(tab_contents) {
+  CHECK(switch_utils::IsActionBoxEnabled())
+      << "Without this, extension->script_badge() would return NULL.";

[not at google - send to devlin, 2012/06/18 18:51:24]

Is this necessary? We only construct these objects when this flag (soon-to-be
enable-script-badges) is true. If anything, (D)CHECK below that script_badge
returns non-NULL.

[Jeffrey Yasskin, 2012/06/18 22:16:03]

The CHECK is intended to tell people reading the code that you only construct
these objects when this flag is true. As the code was, I had to ask you. I could
remove the "Without this..." comment if you want.

[not at google - send to devlin, 2012/06/18 22:59:41]

Maybe just a comment would be more appropriate then?

// Note: this class will only be constructed from ExtensionTabHelper if
// script badges have been enabled.

or something. And a DCHECK if you really want.

[Jeffrey Yasskin, 2012/06/18 23:58:41]

I put the comment inside the DCHECK.

For future reference, what's the convention for deciding between CHECK and
DCHECK when flagging impossible situations?

[not at google - send to devlin, 2012/06/19 00:27:32]

I think of DCHECK as documentation and CHECK as bug-catching.

So in this case, if ScriptBadgeController was instantiated without that flag, no
biggie. But it can't possibly be because forces outside its control never do so.

[Jeffrey Yasskin, 2012/06/19 21:43:08]

Now that script_badge() always returns non-NULL, I think the CHECK isn't needed,
and it requires the switch-overriding machinery, so it's gone.

+}
 
 ScriptBadgeController::~ScriptBadgeController() {}
 
 scoped_ptr<std::vector<ExtensionAction*> >
 ScriptBadgeController::GetCurrentActions() {
   scoped_ptr<std::vector<ExtensionAction*> > current_actions(
       new std::vector<ExtensionAction*>());
 
   ExtensionService* service = GetExtensionService();
   if (!service)
     return current_actions.Pass();
 
   for (ExtensionSet::const_iterator it = service->extensions()->begin();
        it != service->extensions()->end(); ++it) {
     const Extension* extension = *it;
     if (extensions_executing_scripts_.count(extension->id()))
-      current_actions->push_back(extension->GetScriptBadge());
+      current_actions->push_back(extension->script_badge());
   }
   return current_actions.Pass();
 }
 
 LocationBarController::Action ScriptBadgeController::OnClicked(
     const std::string& extension_id, int mouse_button) {
   ExtensionService* service = GetExtensionService();
   if (!service)
     return ACTION_NONE;
 
@@ skipping 87 matching lines @@
   if (page_id == GetPageID()) {
     size_t original_size = extensions_executing_scripts_.size();
     extensions_executing_scripts_.insert(extension_ids.begin(),
                                          extension_ids.end());
     if (extensions_executing_scripts_.size() > original_size)
       Notify();
   }
 }
 
 }  // namespace extensions