Migrate PingLoader to be a LocalFrameLifecycleObserver.

Source/core/loader/BeaconLoader.cpp

 // Copyright 2014 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 "config.h"
 #include "core/loader/BeaconLoader.h"
 
 #include "core/dom/DOMArrayBufferView.h"
 #include "core/dom/Document.h"
 #include "core/fetch/CrossOriginAccessControl.h"
@@ skipping 130 matching lines @@
     ResourceRequest& newRequest(passedNewRequest.toMutableResourceRequest());
     const ResourceResponse& redirectResponse(passedRedirectResponse.toResourceResponse());
 
     ASSERT(!newRequest.isNull());
     ASSERT(!redirectResponse.isNull());
 
     String errorDescription;
     StoredCredentials withCredentials = AllowStoredCredentials;
     ResourceLoaderOptions options;
     if (!CrossOriginAccessControl::handleRedirect(m_beaconOrigin.get(), newRequest, redirectResponse, withCredentials, options, errorDescription)) {
-        if (page() && page()->mainFrame()) {
-            if (page()->mainFrame()->isLocalFrame()) {
-                LocalFrame* localFrame = toLocalFrame(page()->mainFrame());
-                if (localFrame->document())
-                    localFrame->document()->addConsoleMessage(ConsoleMessage::create(JSMessageSource, ErrorMessageLevel, errorDescription));
-            }
+        if (LocalFrame* localFrame = frame()) {
+            if (localFrame->document())
+                localFrame->document()->addConsoleMessage(ConsoleMessage::create(JSMessageSource, ErrorMessageLevel, errorDescription));
         }
         // Cancel the load and self destruct.
         dispose();
         return;
     }
     // FIXME: http://crbug.com/427429 is needed to correctly propagate
     // updates of Origin: following this successful redirect.
 }
 
 namespace {
@@ skipping 70 matching lines @@
     request.setHTTPBody(entityBody.release());
     request.setHTTPContentType(contentType);
 
     payloadLength = entitySize;
     return true;
 }
 
 } // namespace
 
 } // namespace blink