Rename mash_shell to mash_session.

mash/session/public/interfaces/session.mojom

Index: mash/session/public/interfaces/session.mojom
diff --git a/mash/shell/public/interfaces/shell.mojom b/mash/session/public/interfaces/session.mojom
similarity index 91%
rename from mash/shell/public/interfaces/shell.mojom
rename to mash/session/public/interfaces/session.mojom
index 77d1e80a12ba75b422fd91f55693f26cf73bd7f5..f81e98df04ed50f9420d05549919f9d6abceb709 100644
--- a/mash/shell/public/interfaces/shell.mojom
+++ b/mash/session/public/interfaces/session.mojom
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-module mash.shell.mojom;
+module mash.session.mojom;
 
 interface ScreenlockStateListener {
   // This method is called when the listener is initially added with the current
@@ -10,7 +10,7 @@ interface ScreenlockStateListener {
   ScreenlockStateChanged(bool locked);
 };
 
-interface Shell {
+interface Session {
   Logout();
   SwitchUser();
   LockScreen();