Patch on top of https://codereview.chromium.org/474593002

content/renderer/service_worker/service_worker_cache_storage_dispatcher.cc

Index: content/renderer/service_worker/service_worker_cache_storage_dispatcher.cc
diff --git a/content/renderer/service_worker/service_worker_cache_storage_dispatcher.cc b/content/renderer/service_worker/service_worker_cache_storage_dispatcher.cc
index e620a4423a2dfbf8b815cdb44a50e3f2d5d66b4c..7fed7d3ef0cfb1c82a2158a145c5063cce9b69f6 100644
--- a/content/renderer/service_worker/service_worker_cache_storage_dispatcher.cc
+++ b/content/renderer/service_worker/service_worker_cache_storage_dispatcher.cc
@@ -179,34 +179,48 @@ class ServiceWorkerCacheStorageDispatcher::WebCache
       : dispatcher_(dispatcher), cache_id_(cache_id) {}
 
   virtual ~WebCache() {
-    dispatcher_->onWebCacheDestruction(cache_id_);
+    if (dispatcher_)
+      dispatcher_->onWebCacheDestruction(cache_id_);
   }
 
   // From blink::WebServiceWorkerCache:
   virtual void dispatchMatch(CacheMatchCallbacks* callbacks,
                              const blink::WebServiceWorkerRequest& request,
                              const QueryParams& query_params) {
+    if (!dispatcher_)
+      return;
     dispatcher_->dispatchMatchForCache(cache_id_, callbacks, request,
                                        query_params);
   }
   virtual void dispatchMatchAll(CacheWithResponsesCallbacks* callbacks,
                                 const blink::WebServiceWorkerRequest& request,
                                 const QueryParams& query_params) {
+    if (!dispatcher_)
+      return;
     dispatcher_->dispatchMatchAllForCache(cache_id_, callbacks, request,
                                           query_params);
   }
   virtual void dispatchKeys(CacheWithRequestsCallbacks* callbacks,
                             const blink::WebServiceWorkerRequest* request,
                             const QueryParams& query_params) {
+    if (!dispatcher_)
+      return;
     dispatcher_->dispatchKeysForCache(cache_id_, callbacks, request,
                                       query_params);
   }
   virtual void dispatchBatch(
       CacheWithResponsesCallbacks* callbacks,
       const blink::WebVector<BatchOperation>& batch_operations) {
+    if (!dispatcher_)
+      return;
     dispatcher_->dispatchBatchForCache(cache_id_, callbacks, batch_operations);
   }
 
+  void Disconnect() {
+    DCHECK(dispatcher_);
+    dispatcher_ = NULL;
+  }
+
  private:
   // Not owned. Pointer to a dispatcher to use for sending events.
   ServiceWorkerCacheStorageDispatcher* dispatcher_;
@@ -216,7 +230,8 @@ class ServiceWorkerCacheStorageDispatcher::WebCache
 
 ServiceWorkerCacheStorageDispatcher::ServiceWorkerCacheStorageDispatcher(
     ServiceWorkerScriptContext* script_context)
-  : script_context_(script_context) {}
+    : script_context_(script_context) {
+}
 
 ServiceWorkerCacheStorageDispatcher::~ServiceWorkerCacheStorageDispatcher() {
   ClearCallbacksMapWithErrors(&get_callbacks_);
@@ -229,6 +244,13 @@ ServiceWorkerCacheStorageDispatcher::~ServiceWorkerCacheStorageDispatcher() {
   ClearCallbacksMapWithErrors(&cache_match_all_callbacks_);
   ClearCallbacksMapWithErrors(&cache_keys_callbacks_);
   ClearCallbacksMapWithErrors(&cache_batch_callbacks_);
+
+  WebCacheMap::iterator iter(&web_caches_);
+  while (!iter.IsAtEnd()) {
+    iter.GetCurrentValue()->Disconnect();
+    web_caches_.Remove(iter.GetCurrentKey());
+    iter.Advance();
+  }
 }
 
 bool ServiceWorkerCacheStorageDispatcher::OnMessageReceived(