Deprecate NonThreadSafe in remoting in favor of SequenceChecker.

remoting/host/host_window.h

Index: remoting/host/host_window.h
diff --git a/remoting/host/host_window.h b/remoting/host/host_window.h
index 0a2e309c7168b263313a5b90d02c3e8d5c410468..61099e822c20ed9b568fd6be0de64a99d99167a7 100644
--- a/remoting/host/host_window.h
+++ b/remoting/host/host_window.h
@@ -10,15 +10,15 @@
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
 #include "base/memory/weak_ptr.h"
-#include "base/threading/non_thread_safe.h"
+#include "base/sequence_checker.h"
 
 namespace remoting {
 
 class ClientSessionControl;
 
-class HostWindow : public base::NonThreadSafe {
+class HostWindow {
  public:
-  virtual ~HostWindow() {}
+  virtual ~HostWindow();
 
   // Creates a platform-specific instance of the continue window.
   static std::unique_ptr<HostWindow> CreateContinueWindow();
@@ -32,13 +32,15 @@ class HostWindow : public base::NonThreadSafe {
       const base::WeakPtr<ClientSessionControl>& client_session_control) = 0;
 
  protected:
+  // Let |HostWindowProxy| to call DetachFromSequence() when passing an instance
+  // of |HostWindow| to a different sequence.
+  friend class HostWindowProxy;
+
   HostWindow() {}
 
- private:
-  // Let |HostWindowProxy| to call DetachFromThread() when passing an instance
-  // of |HostWindow| to a different thread.
-  friend class HostWindowProxy;
+  SEQUENCE_CHECKER(sequence_checker_);
 
+ private:
   DISALLOW_COPY_AND_ASSIGN(HostWindow);
 };