Add a function triggering extension installed to ExtensionRegistryObserver

extensions/browser/extension_registry.h

Index: extensions/browser/extension_registry.h
diff --git a/extensions/browser/extension_registry.h b/extensions/browser/extension_registry.h
index d8df24b3653d51b30a7b5996ae96579442d832a9..3844ffce7d731648bb81dd99177e79bfadc9f069 100644
--- a/extensions/browser/extension_registry.h
+++ b/extensions/browser/extension_registry.h
@@ -74,6 +74,12 @@ class ExtensionRegistry : public KeyedService {
   void TriggerOnUnloaded(const Extension* extension,
                          UnloadedExtensionInfo::Reason reason);
 
+  // Invokes the observer method OnExtensionInstalled(). The extension will be

[not at google - send to devlin, 2014/05/16 23:03:35]

OnWillBeInstalled

[limasdf, 2014/05/17 06:16:19]

Done.

+  // installed at the time of the call.

[not at google - send to devlin, 2014/05/16 23:03:35]

second sentence still not quite right? should be "the extension must not be
tracked at the time of the call, and the caller should ensure to track it
afterwards".

[limasdf, 2014/05/17 06:16:19]

Done.

+  void TriggerOnInstalled(const Extension* extension,

[not at google - send to devlin, 2014/05/16 23:03:35]

TriggerOnWillBeInstalled

[limasdf, 2014/05/17 06:16:19]

Done.

+                          bool is_update,
+                          const std::string& old_name);
+
   // Find an extension by ID using |include_mask| to pick the sets to search:
   //  * enabled_extensions()     --> ExtensionRegistry::ENABLED
   //  * disabled_extensions()    --> ExtensionRegistry::DISABLED