Remove all the ephemeral apps code.

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 a3bfeb38cb13dc0d5991d243827157b7195bd5e8..2b984651e18314c47c4d22fca3008bcae820cf60 100644
--- a/extensions/browser/extension_registry_observer.h
+++ b/extensions/browser/extension_registry_observer.h
@@ -45,10 +45,6 @@ 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,
@@ -57,13 +53,12 @@ class ExtensionRegistryObserver {
   // (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.
+  // somewhere and have observers retrieve it. |is_update|, 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 when the installation of |extension| is complete. At this point the