Revert of Remove the code to store and load QUIC server configs in the disk cache.

net/quic/chromium/quic_server_info.h

Index: net/quic/chromium/quic_server_info.h
diff --git a/net/quic/chromium/quic_server_info.h b/net/quic/chromium/quic_server_info.h
index a8185766bff5d2d3cb820c27a919a2a2f9ac29dd..eab5366d92961432124df90a25f2f649617db1f5 100644
--- a/net/quic/chromium/quic_server_info.h
+++ b/net/quic/chromium/quic_server_info.h
@@ -24,6 +24,20 @@
 // crypto config.
 class QUIC_EXPORT_PRIVATE QuicServerInfo {
  public:
+  // Enum to track number of times data read/parse/write API calls of
+  // QuicServerInfo to and from disk cache is called.
+  enum QuicServerInfoAPICall {
+    QUIC_SERVER_INFO_START = 0,
+    QUIC_SERVER_INFO_WAIT_FOR_DATA_READY = 1,
+    QUIC_SERVER_INFO_PARSE = 2,
+    QUIC_SERVER_INFO_WAIT_FOR_DATA_READY_CANCEL = 3,
+    QUIC_SERVER_INFO_READY_TO_PERSIST = 4,
+    QUIC_SERVER_INFO_PERSIST = 5,
+    QUIC_SERVER_INFO_EXTERNAL_CACHE_HIT = 6,
+    QUIC_SERVER_INFO_RESET_WAIT_FOR_DATA_READY = 7,
+    QUIC_SERVER_INFO_NUM_OF_API_CALLS = 8,
+  };
+
   // Enum to track failure reasons to read/load/write of QuicServerInfo to
   // and from disk cache.
   enum FailureReason {
@@ -45,12 +59,48 @@
   explicit QuicServerInfo(const QuicServerId& server_id);
   virtual ~QuicServerInfo();
 
-  // Fetches the server config from the backing store, and returns true
-  // if the server config was found.
-  virtual bool Load() = 0;
+  // Start will commence the lookup. This must be called before any other
+  // methods. By opportunistically calling this early, it may be possible to
+  // overlap this object's lookup and reduce latency.
+  virtual void Start() = 0;
 
-  // Persist allows for the server information to be updated for future uses.
+  // WaitForDataReady returns OK if the fetch of the requested data has
+  // completed. Otherwise it returns ERR_IO_PENDING and will call |callback| on
+  // the current thread when ready.
+  //
+  // Only a single callback can be outstanding at a given time and, in the
+  // event that WaitForDataReady returns OK, it's the caller's responsibility
+  // to delete |callback|.
+  //
+  // |callback| may be NULL, in which case ERR_IO_PENDING may still be returned
+  // but, obviously, a callback will never be made.
+  virtual int WaitForDataReady(const CompletionCallback& callback) = 0;
+
+  // Reset's WaitForDataReady callback. This method shouldn't have any side
+  // effects (could be called even if HttpCache doesn't exist).
+  virtual void ResetWaitForDataReadyCallback() = 0;
+
+  // Cancel's WaitForDataReady callback. |callback| passed in WaitForDataReady
+  // will not be called.
+  virtual void CancelWaitForDataReadyCallback() = 0;
+
+  // Returns true if data is loaded from disk cache and ready (WaitForDataReady
+  // doesn't have a pending callback).
+  virtual bool IsDataReady() = 0;
+
+  // Returns true if the object is ready to persist data, in other words, if
+  // data is loaded from disk cache and ready and there are no pending writes.
+  virtual bool IsReadyToPersist() = 0;
+
+  // Persist allows for the server information to be updated for future users.
+  // This is a fire and forget operation: the caller may drop its reference
+  // from this object and the store operation will still complete. This can
+  // only be called once WaitForDataReady has returned OK or called its
+  // callback.
   virtual void Persist() = 0;
+
+  // Called whenever an external cache reuses quic server config.
+  virtual void OnExternalCacheHit() = 0;
 
   // Returns the size of dynamically allocated memory in bytes.
   virtual size_t EstimateMemoryUsage() const = 0;
@@ -79,6 +129,14 @@
   const State& state() const;
   State* mutable_state();
 
+  base::TimeTicks wait_for_data_start_time() const {
+    return wait_for_data_start_time_;
+  }
+
+  base::TimeTicks wait_for_data_end_time() const {
+    return wait_for_data_end_time_;
+  }
+
  protected:
   // Parse parses pickled data and fills out the public member fields of this
   // object. It returns true iff the parse was successful. The public member
@@ -87,6 +145,10 @@
   std::string Serialize();
 
   State state_;
+
+  // Time when WaitForDataReady was called and when it has finished.
+  base::TimeTicks wait_for_data_start_time_;
+  base::TimeTicks wait_for_data_end_time_;
 
   // This is the QUIC server (hostname, port, is_https, privacy_mode) tuple for
   // which we restore the crypto_config.
@@ -102,6 +164,20 @@
   DISALLOW_COPY_AND_ASSIGN(QuicServerInfo);
 };
 
+class QUIC_EXPORT_PRIVATE QuicServerInfoFactory {
+ public:
+  QuicServerInfoFactory() {}
+  virtual ~QuicServerInfoFactory();
+
+  // GetForServer returns a fresh, allocated QuicServerInfo for the given
+  // |server_id| or NULL on failure.
+  virtual std::unique_ptr<QuicServerInfo> GetForServer(
+      const QuicServerId& server_id) = 0;
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(QuicServerInfoFactory);
+};
+
 }  // namespace net
 
 #endif  // NET_QUIC_CHROMIUM_QUIC_SERVER_INFO_H_