Headers for resource tracking.

chrome/browser/offline_pages/offliner_user_data.cc

+// Copyright 2017 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/offline_pages/offliner_user_data.h"
+
+#if BUILDFLAG(ENABLE_OFFLINE_PAGES)
+#include "chrome/browser/offline_pages/background_loader_offliner.h"
+#endif
+
+class ResourceTrackerObserver;
+
+namespace offline_pages {
+
+void OfflinerUserData::AddToWebContents(content::WebContents* webcontents,
+                                        Offliner* offliner) {
+  DCHECK(offliner);
+  webcontents->SetUserData(UserDataKey(), std::unique_ptr<OfflinerUserData>(

[RyanSturm, 2017/06/16 17:04:45]

nit, feel free to leave it as is:

Would it make more sense to call CreateForWebContents and then add a method
(Init) for adding |offliner| to the OfflinerUserData?

You could do that directly in BackgroundLoaderOffliner::AttachObservers since
it's only a couple lines as well.

[Pete Williamson, 2017/06/16 21:16:15]

I could make that change, but it feels like one more step I could forget to do,
since this method does both creation and setting the offliner, and we always
need to do both.

+                                              new OfflinerUserData(offliner)));
+}
+
+// static - gets the data pointer as a BackgroundLoaderOffliner
+Offliner* OfflinerUserData::OfflinerFromWebContents(
+    content::WebContents* webcontents) {
+  OfflinerUserData* data = OfflinerUserData::FromWebContents(webcontents);
+  if (data)
+    return data->offliner();
+
+  return nullptr;
+}
+
+// static - gets the data pointer as a ResourceTrackerObserver

[RyanSturm, 2017/06/16 17:04:45]

s/ResourceTrackerObserver/ResourceLoadingObserver/

[Pete Williamson, 2017/06/16 21:16:15]

Done.

+ResourceLoadingObserver*
+OfflinerUserData::ResourceTrackerObserverFromWebContents(
+    content::WebContents* webcontents) {
+  OfflinerUserData* data = OfflinerUserData::FromWebContents(webcontents);
+  if (data)
+    return static_cast<ResourceLoadingObserver*>(

[RyanSturm, 2017/06/16 17:04:45]

nit: Not sure this first static_case makes things clearer or more confusing.
Since BackgroundLoaderOffliner is a sub class of ResourceLoadingObserver, you
might want to just let the method/compiler downcast it.

[Pete Williamson, 2017/06/16 21:16:15]

I was able to get rid of both casts by changing the observer* to a
BackgroundLoadingObserver*

+        static_cast<offline_pages::BackgroundLoaderOffliner*>(
+            data->offliner()));
+
+  return nullptr;
+}
+
+}  // namespace offline_pages
+
+DEFINE_WEB_CONTENTS_USER_DATA_KEY(offline_pages::OfflinerUserData);