Revert "libmojo: Uprev the library to r456626 from Chromium"

This reverts commit 8ac9103e05b66812c25348943383f9365d1ce3e0.

Reason for revert: Broke the mac_sdk
Exempt-From-Owner-Approval: Fixing mac_sdk

Change-Id: I0b74d1abaa66933a93fd6f82ff018e8948c1204e
diff --git a/base/android/java_handler_thread.h b/base/android/java_handler_thread.h
index 96f2f0a..1709ff4 100644
--- a/base/android/java_handler_thread.h
+++ b/base/android/java_handler_thread.h
@@ -14,6 +14,7 @@
 namespace base {
 
 class MessageLoop;
+class WaitableEvent;
 
 namespace android {
 
@@ -40,15 +41,10 @@
                   const JavaParamRef<jobject>& obj,
                   jlong event);
 
-  virtual void StartMessageLoop();
-  virtual void StopMessageLoop();
-
   static bool RegisterBindings(JNIEnv* env);
 
- protected:
-  std::unique_ptr<base::MessageLoop> message_loop_;
-
  private:
+  std::unique_ptr<base::MessageLoop> message_loop_;
   ScopedJavaGlobalRef<jobject> java_thread_;
 };