Optimize promotion of ephemeral apps

extensions/browser/extension_registry_observer.h

Index: extensions/browser/extension_registry_observer.h
diff --git a/extensions/browser/extension_registry_observer.h b/extensions/browser/extension_registry_observer.h
index b6cf8e0907fe34843a5fc5504d4e2d55bb290a09..7cb524ececac01ced97439a95eda529489447df2 100644
--- a/extensions/browser/extension_registry_observer.h
+++ b/extensions/browser/extension_registry_observer.h
@@ -37,16 +37,25 @@ class ExtensionRegistryObserver {
   // Called when |extension| is about to be installed. |is_update| is true if
   // the installation is the result of it updating, in which case |old_name| is
   // the name of the extension's previous version.
+  // If true, |from_ephemeral| indicates that the extension was previously
+  // installed ephemerally and has been promoted to a regular installed
+  // extension. |is_update| will be true, although the version has not
+  // necessarily changed.
   // The ExtensionRegistry will not be tracking |extension| at the time this
   // event is fired, but will be immediately afterwards (note: not necessarily
   // enabled; it might be installed in the disabled or even blacklisted sets,
   // for example).
   // Note that it's much more common to care about extensions being loaded
   // (OnExtensionLoaded).
+  //
+  // TODO(tmdiep): We should stash the state of the previous extension version
+  // somewhere and have observers retrieve it. |is_update|, |from_ephemeral|
+  // and |old_name| can be removed when this is done.
   virtual void OnExtensionWillBeInstalled(
       content::BrowserContext* browser_context,
       const Extension* extension,
       bool is_update,
+      bool from_ephemeral,
       const std::string& old_name) {}
 
   // Called after an extension is uninstalled. The extension no longer exsit in