Connect to DesktopEnvironment's stubs only when audio/video schedulers are about to be created.

remoting/protocol/input_event_tracker.h

Index: remoting/protocol/input_event_tracker.h
diff --git a/remoting/protocol/input_event_tracker.h b/remoting/protocol/input_event_tracker.h
index 794fffe936c24eb9ecc47f1b06cf925d55d233d7..59733f3a732e7c1ced6a8dee06a3fb30a4ae5022 100644
--- a/remoting/protocol/input_event_tracker.h
+++ b/remoting/protocol/input_event_tracker.h
@@ -20,9 +20,12 @@ namespace protocol {
 // |input_stub| for all currently-pressed keys and buttons when necessary.
 class InputEventTracker : public InputStub {
  public:
-  explicit InputEventTracker(protocol::InputStub* input_stub);
+  explicit InputEventTracker(InputStub* input_stub);
   virtual ~InputEventTracker();
 
+  // Sets the InputStub that sends events to the client.
+  void set_input_stub(InputStub* input_stub) { input_stub_ = input_stub; }

[Wez, 2013/01/08 18:34:00]

Why not derived from InputFilter to get this, and replace input_stub->Foo()
calls w/ InputFilter::Foo()?

[Wez, 2013/01/08 18:34:00]

The problem with this is that it creates the question of the InputEventTracker's
semantics when |input_stub| is null. If you instead just add an InputFilter in
ClientSession, to pass to the InputEventTracker, then that becomes
ClientSession's problem, and ClientSession is in a position to arrange the right
release / NULLify ordering. 

[alexeypa (please no reviews), 2013/01/08 20:00:14]

Done.

+
   // Returns true if the key with the specified USB code is currently pressed.
   bool IsKeyPressed(uint32 usb_keycode) const;