Retry: sync: Gracefully handle early shutdown

sync/internal_api/public/http_bridge.h

Index: sync/internal_api/public/http_bridge.h
diff --git a/sync/internal_api/public/http_bridge.h b/sync/internal_api/public/http_bridge.h
index cbee77112f86bdc32b7204cac51a22796debeab9..c8a21b97157a19dc4d63fe939ee5ef78fdabf7ea 100644
--- a/sync/internal_api/public/http_bridge.h
+++ b/sync/internal_api/public/http_bridge.h
@@ -19,6 +19,7 @@
 #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"
@@ -37,6 +38,8 @@ class URLFetcher;
 
 namespace syncer {
 
+class CancelationSignal;
+
 // Callback for updating the network time.
 // Params:
 // const base::Time& network_time - the new network time.
@@ -229,31 +232,44 @@ class SYNC_EXPORT_PRIVATE HttpBridge
   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 OnStopRequested() 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);
 };