mus: Add PointerWatcher for passively observing mouse and touch events

ash/shell_delegate.h

Index: ash/shell_delegate.h
diff --git a/ash/shell_delegate.h b/ash/shell_delegate.h
index e3c6f5f98e6d5bfc1154370c350aaabd5e53a0cc..b89a408fb59e3f69af5cbbcf14cbe2b669c4b3b9 100644
--- a/ash/shell_delegate.h
+++ b/ash/shell_delegate.h
@@ -40,6 +40,7 @@ namespace ash {
 class AccessibilityDelegate;
 class MediaDelegate;
 class NewWindowDelegate;
+class PointerWatcherDelegate;
 class SessionStateDelegate;
 class ShelfDelegate;
 class ShelfModel;
@@ -138,6 +139,9 @@ class ASH_EXPORT ShellDelegate {
   // Creates a media delegate. Shell takes ownership of the delegate.
   virtual MediaDelegate* CreateMediaDelegate() = 0;
 
+  // Shell takes ownership of the delegate.
+  virtual PointerWatcherDelegate* CreatePointerWatcherDelegate() = 0;

[sky, 2016/04/26 16:55:48]

unique_ptr?

[James Cook, 2016/04/26 17:42:45]

Done.

+
   // Creates a menu model for the |shelf| and optional shelf |item|.
   // If |item| is null, this creates a context menu for the desktop or shelf.
   virtual ui::MenuModel* CreateContextMenu(ash::Shelf* shelf,