Remove enable_notifications build flag and define

chrome/browser/chrome_content_browser_client.cc

Index: chrome/browser/chrome_content_browser_client.cc
diff --git a/chrome/browser/chrome_content_browser_client.cc b/chrome/browser/chrome_content_browser_client.cc
index 4404b067e1c9fb2c3f7f138ed2803f4ffd4105a7..b9b8d6659616103667c4bdf92d363b69f4f405ba 100644
--- a/chrome/browser/chrome_content_browser_client.cc
+++ b/chrome/browser/chrome_content_browser_client.cc
@@ -2269,12 +2269,7 @@ content::MediaObserver* ChromeContentBrowserClient::GetMediaObserver() {
 
 content::PlatformNotificationService*
 ChromeContentBrowserClient::GetPlatformNotificationService() {
-#if defined(ENABLE_NOTIFICATIONS)
   return PlatformNotificationServiceImpl::GetInstance();
-#else
-  NOTIMPLEMENTED();
-  return NULL;
-#endif
 }
 
 bool ChromeContentBrowserClient::CanCreateWindow(