[Hotword] Uninstall and reinstall the extension upon language change.

chrome/browser/search/hotword_service.h

Index: chrome/browser/search/hotword_service.h
diff --git a/chrome/browser/search/hotword_service.h b/chrome/browser/search/hotword_service.h
index a30753343ca8983fb6bf66d8215663935ca499d7..ece6eba732a08591ef2800612be2c6ccc28d3678 100644
--- a/chrome/browser/search/hotword_service.h
+++ b/chrome/browser/search/hotword_service.h
@@ -6,15 +6,24 @@
 #define CHROME_BROWSER_SEARCH_HOTWORD_SERVICE_H_
 
 #include "base/basictypes.h"
+#include "base/memory/weak_ptr.h"
 #include "base/prefs/pref_change_registrar.h"
+#include "base/scoped_observer.h"
 #include "components/keyed_service/core/keyed_service.h"
 #include "content/public/browser/notification_observer.h"
 #include "content/public/browser/notification_registrar.h"
+#include "extensions/browser/extension_registry.h"
+#include "extensions/browser/extension_registry_observer.h"
 
 class ExtensionService;
 class HotwordClient;
 class Profile;
 
+namespace extensions {
+class Extension;
+class WebstoreStandaloneInstaller;
+}  // namespace extensions
+
 namespace hotword_internal {
 // Constants for the hotword field trial.
 extern const char kHotwordFieldTrialName[];
@@ -24,6 +33,7 @@ extern const char kHotwordFieldTrialDisabledGroupName[];
 // Provides an interface for the Hotword component that does voice triggered
 // search.
 class HotwordService : public content::NotificationObserver,
+                       public extensions::ExtensionRegistryObserver,
                        public KeyedService {
  public:
   // Returns true if the hotword supports the current system language.
@@ -37,6 +47,14 @@ class HotwordService : public content::NotificationObserver,
                        const content::NotificationSource& source,
                        const content::NotificationDetails& details) OVERRIDE;
 
+  // Overridden from ExtensionRegisterObserver:
+  virtual void OnExtensionInstalled(
+      content::BrowserContext* browser_context,
+      const extensions::Extension* extension) OVERRIDE;
+  virtual void OnExtensionUninstalled(
+      content::BrowserContext* browser_context,
+      const extensions::Extension* extension) OVERRIDE;
+
   // Checks for whether all the necessary files have downloaded to allow for
   // using the extension.
   virtual bool IsServiceAvailable();
@@ -62,6 +80,23 @@ class HotwordService : public content::NotificationObserver,
   void StopHotwordSession(HotwordClient* client);
   HotwordClient* client() { return client_; }
 
+  // Checks if the current version of the hotword extension should be
+  // uninstalled in order to update to a different language version.
+  // Returns true if the extension was uninstalled.
+  bool MaybeReinstallHotwordExtension();
+
+  // Checks based on locale if the current version should be uninstalled so that
+  // a version with a different language can be installed.
+  bool ShouldReinstallHotwordExtension();
+
+  // Helper functions pulled out for testing purposes.
+  // UninstallHotwordExtension returns true if the extension was uninstalled.
+  virtual bool UninstallHotwordExtension(ExtensionService* extension_service);
+  virtual void InstallHotwordExtensionFromWebstore();
+
+  // Sets the pref value of the previous language.
+  void SetPreviousLanguagePref();
+
   // Returns the current error message id. A value of 0 indicates
   // no error.
   int error_message() { return error_message_; }
@@ -73,8 +108,18 @@ class HotwordService : public content::NotificationObserver,
 
   content::NotificationRegistrar registrar_;
 
+  // For observing the ExtensionRegistry.
+  ScopedObserver<extensions::ExtensionRegistry,
+                 extensions::ExtensionRegistryObserver>
+      extension_registry_observer_;
+
+  scoped_refptr<extensions::WebstoreStandaloneInstaller> installer_;
+
   HotwordClient* client_;
   int error_message_;
+  bool reinstall_pending_;
+
+  base::WeakPtrFactory<HotwordService> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(HotwordService);
 };