Use the previews black list for offline previews

chrome/browser/android/offline_pages/offline_page_request_interceptor.h

 // Copyright 2016 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.
 
 #ifndef CHROME_BROWSER_ANDROID_OFFLINE_PAGES_OFFLINE_PAGE_REQUEST_INTERCEPTOR_H_
 #define CHROME_BROWSER_ANDROID_OFFLINE_PAGES_OFFLINE_PAGE_REQUEST_INTERCEPTOR_H_
 
 #include "base/macros.h"
 #include "net/url_request/url_request_interceptor.h"
 
 namespace net {
 class NetworkDelegate;
 class URLRequest;
 class URLRequestJob;
 }
 
+namespace previews {
+class PreviewsBlackList;
+}
+
 namespace offline_pages {
 
 // An interceptor to hijack requests and potentially service them based on
 // their offline information. Created one per profile.
 class OfflinePageRequestInterceptor : public net::URLRequestInterceptor {
  public:
-  OfflinePageRequestInterceptor();
+  OfflinePageRequestInterceptor(

[tbansal1, 2016/10/04 12:38:04]

explicit

[RyanSturm, 2016/10/04 21:36:37]

Done.

+      previews::PreviewsBlackList* previews_black_list);
   ~OfflinePageRequestInterceptor() override;
 
  private:
   // Overrides from net::URLRequestInterceptor:
   net::URLRequestJob* MaybeInterceptRequest(
       net::URLRequest* request,
       net::NetworkDelegate* network_delegate) const override;
 
+  // Used to determine if an URLRequest is eligible for offline previews.
+  previews::PreviewsBlackList* previews_black_list_;

[jianli, 2016/10/03 22:56:05]

Who owns this? What's lifetime model for this? It just seems risky to pass a raw
pointer without any hints.

[RyanSturm, 2016/10/03 23:54:38]

This is owned by PreviewsIOData, which is created and initialized for each
profile before OfflinePageRequestInterceptor. Both of these are ultimately owned
by ProfileImpl, and will both be destroyed during shutdown. This should be safe
as a raw pointer, and I'm not sure of a better way to get this in besides
dependency injection.

The only other option would be to put it in URLRequestContext, which really
makes no sense as previews have nothing to do with net/.

I'm not sure what you mean by hints, but I can add a comment that the embedder
should guarantee that |previews_black_list| outlives |this|.

WDYT?

+
   DISALLOW_COPY_AND_ASSIGN(OfflinePageRequestInterceptor);
 };
 
 }  // namespace offline_pages
 
 #endif // CHROME_BROWSER_ANDROID_OFFLINE_PAGES_OFFLINE_PAGE_REQUEST_INTERCEPTOR_H_