Makes ash/mus use RootWindowControllerCommon

ash/common/shell_window_ids.h

Index: ash/common/shell_window_ids.h
diff --git a/ash/common/shell_window_ids.h b/ash/common/shell_window_ids.h
index 8681e9c5d44b01e4c39077611d8583431bfc8dca..93208122c59714c370d5f1cc1366010fcfcef572 100644
--- a/ash/common/shell_window_ids.h
+++ b/ash/common/shell_window_ids.h
@@ -9,6 +9,9 @@
 
 namespace ash {
 
+// Used to indicate no shell window id.
+const int kShellWindowId_Invalid = -1;
+
 // A higher-level container that holds all of the containers stacked below
 // kShellWindowId_LockScreenContainer.  Only used by PowerButtonController for
 // animating lower-level containers.
@@ -33,6 +36,7 @@ const int kShellWindowId_UnparentedControlContainer = 3;
 const int kShellWindowId_DesktopBackgroundContainer = 4;
 
 // The virtual keyboard container.
+// NOTE: this is lazily created.
 const int kShellWindowId_VirtualKeyboardContainer = 5;
 
 // The container for standard top-level windows.
@@ -99,6 +103,9 @@ const int kShellWindowId_MouseCursorContainer = 24;
 // The topmost container, used for power off animation.
 const int kShellWindowId_PowerButtonAnimationContainer = 25;
 
+const int kShellWindowId_Min = 0;
+const int kShellWindowId_Max = kShellWindowId_PowerButtonAnimationContainer;
+
 // TODO(sky): remove. Temporary for rietveld to pick up file move rather than
 // new file.