This patch improves the way that GuestViewManager tracks the destruction of GuestView embedders.

extensions/browser/browser_context_keyed_api_factory.h

 // Copyright 2014 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 EXTENSIONS_BROWSER_BROWSER_CONTEXT_KEYED_API_FACTORY_H_
 #define EXTENSIONS_BROWSER_BROWSER_CONTEXT_KEYED_API_FACTORY_H_
 
 #include "components/keyed_service/content/browser_context_dependency_manager.h"
 #include "components/keyed_service/content/browser_context_keyed_service_factory.h"
 #include "components/keyed_service/core/keyed_service.h"
@@ skipping 58 matching lines @@
 // a KeyedService that uses this factory template instead of its own separate
 // factory definition to manage its per-profile instances.
 template <typename T>
 class BrowserContextKeyedAPIFactory : public BrowserContextKeyedServiceFactory {
  public:
   static T* Get(content::BrowserContext* context) {
     return static_cast<T*>(
         T::GetFactoryInstance()->GetServiceForBrowserContext(context, true));
   }
 
+  static T* GetIfExists(content::BrowserContext* context) {
+    return static_cast<T*>(
+        T::GetFactoryInstance()->GetServiceForBrowserContext(context, false));
+  }
+
   // Declare dependencies on other factories.
   // By default, ExtensionSystemFactory is the only dependency; however,
   // specializations can override this. Declare your specialization in
   // your header file after the BrowserContextKeyedAPI class definition.
   // Then in the cc file (or inline in the header), define it, e.g.:
   //   template <>
   //   void BrowserContextKeyedAPIFactory<
   //       PushMessagingAPI>::DeclareFactoryDependencies() {
   //     DependsOn(ExtensionsBrowserClient::Get()->GetExtensionSystemFactory());
   //     DependsOn(ProfileSyncServiceFactory::GetInstance());
@@ skipping 38 matching lines @@
   bool ServiceIsNULLWhileTesting() const override {
     return T::kServiceIsNULLWhileTesting;
   }
 
   DISALLOW_COPY_AND_ASSIGN(BrowserContextKeyedAPIFactory);
 };
 
 }  // namespace extensions
 
 #endif  // EXTENSIONS_BROWSER_BROWSER_CONTEXT_KEYED_API_FACTORY_H_