Remove no-longer-needed IsBusy...() stuff.

mojo/edk/system/dispatcher.h

Index: mojo/edk/system/dispatcher.h
diff --git a/mojo/edk/system/dispatcher.h b/mojo/edk/system/dispatcher.h
index c4903429adec6d7c10b91bfd9ddca2c47cb6d392..30e2d5d8934e37a01d41a92e4634285042eaaf41 100644
--- a/mojo/edk/system/dispatcher.h
+++ b/mojo/edk/system/dispatcher.h
@@ -380,11 +380,6 @@ class Dispatcher : public util::RefCountedThreadSafe<Dispatcher> {
       std::vector<platform::ScopedPlatformHandle>* platform_handles)
       MOJO_NOT_THREAD_SAFE;
 
-  // This should be overridden to return true if/when there's an ongoing
-  // operation (e.g., two-phase read/writes on data pipes) that should prevent a
-  // handle from being sent over a message pipe (with status "busy").
-  virtual bool IsBusyNoLock() const MOJO_SHARED_LOCKS_REQUIRED(mutex_);
-
   util::Mutex& mutex() const MOJO_LOCK_RETURNED(mutex_) { return mutex_; }
 
  private: