Make SDCH dictionaries persistent across browser restart.

net/url_request/sdch_dictionary_fetcher.h

Index: net/url_request/sdch_dictionary_fetcher.h
diff --git a/net/url_request/sdch_dictionary_fetcher.h b/net/url_request/sdch_dictionary_fetcher.h
index 79d87782e13ece5ef53f671d86409daed0745897..4c2db840dac6dc979f087134c91a2d626a6d717f 100644
--- a/net/url_request/sdch_dictionary_fetcher.h
+++ b/net/url_request/sdch_dictionary_fetcher.h
@@ -35,8 +35,14 @@ class URLRequestThrottlerEntryInterface;
 class NET_EXPORT SdchDictionaryFetcher : public URLRequest::Delegate,
                                          public base::NonThreadSafe {
  public:
+  class Data {
+   public:
+    virtual ~Data() {}
+  };
+
   typedef base::Callback<void(const std::string& dictionary_text,
                               const GURL& dictionary_url,
+                              scoped_ptr<Data> extra_data,
                               const BoundNetLog& net_log)>
       OnDictionaryFetchedCallback;
 
@@ -48,8 +54,14 @@ class NET_EXPORT SdchDictionaryFetcher : public URLRequest::Delegate,
                         const OnDictionaryFetchedCallback& callback);
   ~SdchDictionaryFetcher() override;
 
-  // Request a new dictionary fetch.
-  void Schedule(const GURL& dictionary_url);
+  // Request a new dictionary fetch.  |extra_data| is data that will be
+  // returned in the OnDictionaryFetchedCallback if the dictionary fetch
+  // succeeds; otherwise it will be destroyed.
+  void Schedule(const GURL& dictionary_url, scoped_ptr<Data> extra_data);
+
+  // Request a dictionary fetch from cache only.  See comment above
+  // for information on |extra_data|.
+  void ScheduleReload(const GURL& dictionary_url, scoped_ptr<Data> extra_data);
 
   // Cancel any in-progress requests.
   void Cancel();
@@ -67,6 +79,32 @@ class NET_EXPORT SdchDictionaryFetcher : public URLRequest::Delegate,
     STATE_REQUEST_COMPLETE,
   };
 
+  struct QueuedInfo {
+    const GURL url;
+    bool download_only_from_cache;
+
+    // Owned by |fetch_queue_|; must be destroyed if queue entry is
+    // dropped.  Not a scoped_ptr<> as std::queue requires copyable
+    // types.
+    Data* extra_data;
+
+    QueuedInfo() : download_only_from_cache(false), extra_data(nullptr) {}
+    QueuedInfo(const GURL& url,
+               bool download_only_from_cache,
+               scoped_ptr<Data> extra_data);
+    QueuedInfo(const QueuedInfo& rhs) = default;
+    QueuedInfo& operator=(const QueuedInfo& rhs) = default;
+  };
+
+  // Schedule implementation.
+  void ScheduleInternal(const GURL& dictionary_url,
+                        bool reload,
+                        scoped_ptr<Data> extra_data);
+
+  // Null out the current request and push the state machine to the
+  // next request, if any.
+  void ResetRequest();
+
   // State machine implementation.
   int DoLoop(int rv);
   int DoDispatchRequest(int rv);
@@ -78,12 +116,15 @@ class NET_EXPORT SdchDictionaryFetcher : public URLRequest::Delegate,
   bool in_loop_;
 
   // A queue of URLs that are being used to download dictionaries.
-  std::queue<GURL> fetch_queue_;
+  // |fetch_queue_[n].second| indicated whether the download should occur
+  // only from cache.
+  std::queue<QueuedInfo> fetch_queue_;
 
-  // The request and buffer used for getting the current dictionary
-  // Both are null when a fetch is not in progress.
+  // The request, buffer, and consumer supplied data used for getting
+  // the current dictionary.  All are null when a fetch is not in progress.
   scoped_ptr<URLRequest> current_request_;
   scoped_refptr<IOBuffer> buffer_;
+  scoped_ptr<Data> current_extra_data_;
 
   // The currently accumulating dictionary.
   std::string dictionary_;