Remove PerBrowser launcher, reland step 1 of 2

ash/launcher/launcher_delegate.h

Index: ash/launcher/launcher_delegate.h
diff --git a/ash/launcher/launcher_delegate.h b/ash/launcher/launcher_delegate.h
index f835aac2822dbe56bd0d023b66b2dfcb6d76fbe7..322df3832c1bdf193fac06743f827e77150daa31 100644
--- a/ash/launcher/launcher_delegate.h
+++ b/ash/launcher/launcher_delegate.h
@@ -46,7 +46,7 @@ class ASH_EXPORT LauncherDelegate {
   // and has an instance of |views::View| as the event target
   // but not |aura::Window|. If the |event| is of type KeyEvent, it is assumed
   // that this was triggered by keyboard action (Alt+<number>) and special
-  // handling might happen (PerApp launcher).
+  // handling might happen.
   virtual void ItemSelected(const LauncherItem& item,
                             const ui::Event& event) = 0;
 
@@ -92,9 +92,6 @@ class ASH_EXPORT LauncherDelegate {
   // exists.
   virtual void OnLauncherDestroyed(Launcher* launcher) = 0;
 
-  // True if the running launcher is the per application launcher.
-  virtual bool IsPerAppLauncher() = 0;
-
   // Get the launcher ID from an application ID.
   virtual LauncherID GetLauncherIDForAppID(const std::string& app_id) = 0;