Remove content::NotificationObserver dependency from most Prefs code.

chrome/browser/ui/webui/ntp/ntp_resource_cache_android.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/ui/webui/ntp/ntp_resource_cache.h"
 
 #include "base/command_line.h"
 #include "base/memory/ref_counted_memory.h"
 #include "base/string16.h"
 #include "base/string_piece.h"
@@ skipping 38 matching lines @@
   NOTIMPLEMENTED();
   return NULL;
 }
 
 void NTPResourceCache::Observe(int type,
     const content::NotificationSource& source,
     const content::NotificationDetails& details) {
   // No notifications necessary in Android.
 }
 
+void NTPResourceCache::OnPreferenceChanged(PrefServiceBase* service,
+                                           const std::string& pref_name) {
+  // No notifications necessary in Android.
+}
+
 void NTPResourceCache::CreateNewTabHTML() {
   // TODO(estade): these strings should be defined in their relevant handlers
   // (in GetLocalizedValues) and should have more legible names.
   // Show the profile name in the title and most visited labels if the current
   // profile is not the default.
   DictionaryValue localized_strings;
   localized_strings.SetBoolean("hasattribution", false);
   localized_strings.SetString("title",
       l10n_util::GetStringUTF16(IDS_NEW_TAB_TITLE));
   localized_strings.SetString("mostvisited",
@@ skipping 61 matching lines @@
     size_t after_offset = pos + template_data_placeholder.size();
     full_html.append(new_tab_html.data() + after_offset,
                      new_tab_html.size() - after_offset);
   } else {
     NOTREACHED();
     full_html.assign(new_tab_html.data(), new_tab_html.size());
   }
 
   new_tab_html_ = base::RefCountedString::TakeString(&full_html);
 }