Retry: sync: Gracefully handle early shutdown

sync/internal_api/public/http_bridge.h

 // Copyright 2012 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 SYNC_INTERNAL_API_PUBLIC_HTTP_BRIDGE_H_
 #define SYNC_INTERNAL_API_PUBLIC_HTTP_BRIDGE_H_
 
 #include <string>
 
 #include "base/basictypes.h"
 #include "base/callback.h"
 #include "base/compiler_specific.h"
 #include "base/gtest_prod_util.h"
 #include "base/memory/ref_counted.h"
 #include "base/synchronization/lock.h"
 #include "base/synchronization/waitable_event.h"
 #include "net/base/network_time_notifier.h"
 #include "net/url_request/url_fetcher_delegate.h"
 #include "net/url_request/url_request_context.h"
 #include "net/url_request/url_request_context_getter.h"
 #include "sync/base/sync_export.h"
+#include "sync/internal_api/public/base/cancelation_observer.h"
 #include "sync/internal_api/public/http_post_provider_factory.h"
 #include "sync/internal_api/public/http_post_provider_interface.h"
 #include "url/gurl.h"
 
 class HttpBridgeTest;
 
 namespace base {
 class MessageLoop;
 }
 
 namespace net {
 class HttpResponseHeaders;
 class HttpUserAgentSettings;
 class URLFetcher;
 }
 
 namespace syncer {
 
+class CancelationSignal;
+
 // Callback for updating the network time.
 // Params:
 // const base::Time& network_time - the new network time.
 // const base::TimeDelta& resolution - how precise the reading is.
 // const base::TimeDelta& latency - the http request's latency.
 typedef base::Callback<void(const base::Time&,
                             const base::TimeDelta&,
                             const base::TimeDelta&)> NetworkTimeUpdateCallback;
 
 // A bridge between the syncer and Chromium HTTP layers.
@@ skipping 172 matching lines @@
   scoped_refptr<RequestContextGetter> context_getter_for_request_;
 
   const scoped_refptr<base::SingleThreadTaskRunner> network_task_runner_;
 
   // Callback for updating network time.
   NetworkTimeUpdateCallback network_time_update_callback_;
 
   DISALLOW_COPY_AND_ASSIGN(HttpBridge);
 };
 
-class SYNC_EXPORT HttpBridgeFactory : public HttpPostProviderFactory {
+class SYNC_EXPORT HttpBridgeFactory : public HttpPostProviderFactory,
+                                      public CancelationObserver {
  public:
   HttpBridgeFactory(
       net::URLRequestContextGetter* baseline_context_getter,
-      const std::string& user_agent,
-      const NetworkTimeUpdateCallback& network_time_update_callback);
+      const NetworkTimeUpdateCallback& network_time_update_callback,
+      CancelationSignal* cancelation_signal);
   virtual ~HttpBridgeFactory();
 
   // HttpPostProviderFactory:
+  virtual void Init(const std::string& user_agent) OVERRIDE;
   virtual HttpPostProviderInterface* Create() OVERRIDE;
   virtual void Destroy(HttpPostProviderInterface* http) OVERRIDE;
-  virtual void Shutdown() OVERRIDE;
+
+  // CancelationObserver implementation:
+  virtual void OnSignalReceived() OVERRIDE;
 
  private:
-  // Protects |request_context_getter_|.
+  // Protects |request_context_getter_| and |baseline_request_context_getter_|.
   base::Lock context_getter_lock_;
 
+  // This request context is the starting point for the request_context_getter_
+  // that we eventually use to make requests.  During shutdown we must drop all
+  // references to it before the ProfileSyncService's Shutdown() call is
+  // complete.
+  scoped_refptr<net::URLRequestContextGetter> baseline_request_context_getter_;
+
   // This request context is built on top of the baseline context and shares
-  // common components. It's mostly used on sync thread when creating
-  // connection but is released as soon as possible during shutdown. Protected
-  // by |context_getter_lock_|.
+  // common components. Takes a reference to the
+  // baseline_request_context_getter_.  It's mostly used on sync thread when
+  // creating connection but is released as soon as possible during shutdown.
+  // Protected by |context_getter_lock_|.
   scoped_refptr<HttpBridge::RequestContextGetter> request_context_getter_;
 
   NetworkTimeUpdateCallback network_time_update_callback_;
 
+  CancelationSignal* const cancelation_signal_;
+
   DISALLOW_COPY_AND_ASSIGN(HttpBridgeFactory);
 };
 
 }  //  namespace syncer
 
 #endif  // SYNC_INTERNAL_API_PUBLIC_HTTP_BRIDGE_H_