Fix app_shell shutdown crash due to BrowserContextKeyedServices

chrome/browser/chromeos/drive/drive_integration_service.h

Index: chrome/browser/chromeos/drive/drive_integration_service.h
diff --git a/chrome/browser/chromeos/drive/drive_integration_service.h b/chrome/browser/chromeos/drive/drive_integration_service.h
index 2f6dd45c30978893135fd32ad38f00d939e039d9..3c4394e0bb894810a2897c0c568d60e6dfbcf475 100644
--- a/chrome/browser/chromeos/drive/drive_integration_service.h
+++ b/chrome/browser/chromeos/drive/drive_integration_service.h
@@ -208,7 +208,9 @@ class DriveIntegrationServiceFactory
   static DriveIntegrationServiceFactory* GetInstance();
 
   // Sets a factory function for tests.
-  static void SetFactoryForTest(const FactoryCallback& factory_for_test);
+  // NOTE: Call SetFactoryForTest(NULL) during your test TearDown so you don't
+  // pollute the next test.
+  static void SetFactoryForTest(FactoryCallback* factory_for_test);

[xiyuan, 2014/01/09 17:53:22]

nit: How about making this private and use a
ScopedDriveIntegrationServiceFactoryForTest class to access it and automatically
clears it on destruction?

 
  private:
   friend struct DefaultSingletonTraits<DriveIntegrationServiceFactory>;
@@ -220,7 +222,12 @@ class DriveIntegrationServiceFactory
   virtual BrowserContextKeyedService* BuildServiceInstanceFor(
       content::BrowserContext* context) const OVERRIDE;
 
-  FactoryCallback factory_for_test_;
+  // This is static so it can be set without instantiating the factory. This
+  // allows factory creation to be delayed until it normally happens (on profile
+  // creation) rather than when tests are set up. DriveIntegrationServiceFactory
+  // transitively depends on ExtensionSystemFactory which crashes if created too
+  // soon (i.e. before the BrowserProcess exists).
+  static FactoryCallback* factory_for_test_;
 };
 
 }  // namespace drive