Remove remoting::Clipboard::Stop().

remoting/host/clipboard_mac.mm

Index: remoting/host/clipboard_mac.mm
diff --git a/remoting/host/clipboard_mac.mm b/remoting/host/clipboard_mac.mm
index f3f369eec756be80b9538257714644414538a055..68c753b668a55cdfcf98ee155f503967f9ecbd33 100644
--- a/remoting/host/clipboard_mac.mm
+++ b/remoting/host/clipboard_mac.mm
@@ -33,7 +33,6 @@ class ClipboardMac : public Clipboard {
   // Must be called on the UI thread.
   void Start(scoped_ptr<protocol::ClipboardStub> client_clipboard) override;
   void InjectClipboardEvent(const protocol::ClipboardEvent& event) override;
-  void Stop() override;
 
  private:
   void CheckClipboardForChanges();
@@ -90,11 +89,6 @@ void ClipboardMac::InjectClipboardEvent(const protocol::ClipboardEvent& event) {
   current_change_count_ = [[NSPasteboard generalPasteboard] changeCount];
 }
 
-void ClipboardMac::Stop() {
-  clipboard_polling_timer_.reset();
-  client_clipboard_.reset();
-}
-
 void ClipboardMac::CheckClipboardForChanges() {
   NSPasteboard* pasteboard = [NSPasteboard generalPasteboard];
   NSInteger change_count = [pasteboard changeCount];