Revert 35735 - Relanding the language detection code....

chrome/browser/extensions/extension_tabs_module.cc

Index: chrome/browser/extensions/extension_tabs_module.cc
===================================================================
--- chrome/browser/extensions/extension_tabs_module.cc	(revision 35751)
+++ chrome/browser/extensions/extension_tabs_module.cc	(working copy)
@@ -839,24 +839,15 @@
       return false;
   }
 
-  AddRef();  // Balanced in GotLanguage()
-
-  NavigationEntry* entry = contents->controller().GetActiveEntry();
-  if (entry) {
-    std::string language = entry->language();
-    if (!language.empty()) {
-      // Delay the callback invocation until after the current JS call has
-      // returned.
-      MessageLoop::current()->PostTask(FROM_HERE, NewRunnableMethod(
-          this, &DetectTabLanguageFunction::GotLanguage, language));
-      return true;
-    }
-  }
-  // The tab contents does not know its language yet.  Let's  wait until it
-  // receives it.
+  // Figure out what language |contents| contains. This sends an async call via
+  // the browser to the renderer to determine the language of the tab the
+  // renderer has. The renderer sends back the language of the tab after the
+  // tab loads (it may be delayed) to the browser, which in turn notifies this
+  // object that the language has been received.
+  contents->GetPageLanguage();
   registrar_.Add(this, NotificationType::TAB_LANGUAGE_DETERMINED,
-                 Source<RenderViewHost>(contents->render_view_host()));
-
+      NotificationService::AllSources());
+  AddRef();  // balanced in Observe()
   return true;
 }
 
@@ -865,16 +856,9 @@
                                         const NotificationDetails& details) {
   DCHECK(type == NotificationType::TAB_LANGUAGE_DETERMINED);
   std::string language(*Details<std::string>(details).ptr());
-  registrar_.Remove(this, NotificationType::TAB_LANGUAGE_DETERMINED, source);
-
-  GotLanguage(language);
-}
-
-void DetectTabLanguageFunction::GotLanguage(const std::string& language) {
   result_.reset(Value::CreateStringValue(language.c_str()));
   SendResponse(true);
-
-  Release();  // Balanced in Run()
+  Release();  // balanced in Run()
 }
 
 // static helpers