Clean up threading model of external extension providers

chrome/browser/extensions/extension_service.h

Index: chrome/browser/extensions/extension_service.h
diff --git a/chrome/browser/extensions/extension_service.h b/chrome/browser/extensions/extension_service.h
index 9e4206c5ec52c2aca46140d20b4cb2f435a0c3c2..0f54748902357228017e122d71af8927d158fd6d 100644
--- a/chrome/browser/extensions/extension_service.h
+++ b/chrome/browser/extensions/extension_service.h
@@ -99,6 +99,7 @@ class ExtensionService
     : public base::RefCountedThreadSafe<ExtensionService,
                                         BrowserThread::DeleteOnUIThread>,
       public ExtensionUpdateService,
+      public ExternalExtensionProvider::Visitor,
       public NotificationObserver {
  public:
   // Information about a registered component extension.
@@ -297,10 +298,6 @@ class ExtensionService
   // Check for updates (or potentially new extensions from external providers)
   void CheckForExternalUpdates();
 
-  // Copies the list of force-installed extensions from the user PrefService
-  // to ExternalPolicyExtensionProvider.
-  void UpdateExternalPolicyExtensionProvider();
-
   // Unload the specified extension.
   void UnloadExtension(const std::string& extension_id,
                        UnloadedExtensionInfo::Reason reason);
@@ -342,13 +339,6 @@ class ExtensionService
   // extension.
   const SkBitmap& GetOmniboxPopupIcon(const std::string& extension_id);
 
-  // Clear all ExternalExtensionProviders.
-  void ClearProvidersForTesting();
-
-  // Sets an ExternalExtensionProvider for the service to use during testing.
-  // Takes ownership of |test_provider|.
-  void AddProviderForTesting(ExternalExtensionProvider* test_provider);
-
   // Called when the initial extensions load has completed.
   virtual void OnLoadedInstalledExtensions();
 
@@ -358,12 +348,6 @@ class ExtensionService
   // Called by the backend when an extension has been installed.
   void OnExtensionInstalled(const Extension* extension);
 
-  // Called by the backend when an external extension is found.
-  void OnExternalExtensionFileFound(const std::string& id,
-                                    const std::string& version,
-                                    const FilePath& path,
-                                    Extension::Location location);
-
   // Checks if the privileges requested by |extension| have increased, and if
   // so, disables the extension and prompts the user to approve the change.
   void DisableIfPrivilegeIncrease(const Extension* extension);
@@ -425,6 +409,29 @@ class ExtensionService
   // view has been created.
   void DidCreateRenderViewForBackgroundPage(ExtensionHost* host);
 
+  // For the extension in |version_path| with |id|, check to see if it's an
+  // externally managed extension.  If so, uninstall it.
+  void CheckExternalUninstall(const std::string& id);
+
+  // Clear all ExternalExtensionProviders.
+  void ClearProvidersForTesting();
+
+  // Adds an ExternalExtensionProvider for the service to use during testing.
+  // Takes ownership of |test_provider|.
+  void AddProviderForTesting(ExternalExtensionProvider* test_provider);
+
+  // ExternalExtensionProvider::Visitor implementation.
+  virtual void OnExternalExtensionFileFound(const std::string& id,
+                                            const Version* version,
+                                            const FilePath& path,
+                                            Extension::Location location);
+
+  virtual void OnExternalExtensionUpdateUrlFound(const std::string& id,
+                                                 const GURL& update_url,
+                                                 Extension::Location location);
+
+  virtual void OnExternalProviderReady();
+
   // NotificationObserver
   virtual void Observe(NotificationType type,
                        const NotificationSource& source,
@@ -589,6 +596,16 @@ class ExtensionService
   // Flag to make sure event routers are only initialized once.
   bool event_routers_initialized_;
 
+  // A collection of external extension providers.  Each provider reads
+  // a source of external extension information.  Examples include the
+  // windows registry and external_extensions.json.
+  ProviderCollection external_extension_providers_;
+
+  // Set to true by OnExternalExtensionUpdateUrlFound() when an external
+  // extension URL is found.  Used in CheckForExternalUpdates() to see
+  // if an update check is needed to install pending extensions.
+  bool external_extension_added_;
+
   FRIEND_TEST_ALL_PREFIXES(ExtensionServiceTest,
                            UpdatePendingExtensionAlreadyInstalled);
   FRIEND_TEST_ALL_PREFIXES(ExtensionServiceTest,