Revert of Add GN build rules to allow java_assertion_enabler to enable Java asserts.

media/midi/java/src/org/chromium/midi/MidiManagerAndroid.java

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 package org.chromium.midi;
 
 import android.annotation.TargetApi;
 import android.content.Context;
 import android.media.midi.MidiDevice;
 import android.media.midi.MidiDeviceInfo;
@@ skipping 49 matching lines @@
     @CalledByNative
     static MidiManagerAndroid create(Context context, long nativeManagerPointer) {
         return new MidiManagerAndroid(context, nativeManagerPointer);
     }
 
     /**
      * @param context
      * @param nativeManagerPointer The native pointer to a midi::MidiManagerAndroid object.
      */
     private MidiManagerAndroid(Context context, long nativeManagerPointer) {
-        // TODO(crbug.com/665157)
-        // assert ThreadUtils.runningOnUiThread();
+        assert ThreadUtils.runningOnUiThread();
 
         mManager = (MidiManager) context.getSystemService(Context.MIDI_SERVICE);
         mHandler = new Handler(ThreadUtils.getUiThreadLooper());
         mNativeManagerPointer = nativeManagerPointer;
     }
 
     /**
      * Initializes this object.
      * This function must be called right after creation.
      */
@@ skipping 84 matching lines @@
             mIsInitialized = true;
         }
     }
 
     static native void nativeOnInitialized(
             long nativeMidiManagerAndroid, MidiDeviceAndroid[] devices);
     static native void nativeOnInitializationFailed(long nativeMidiManagerAndroid);
     static native void nativeOnAttached(long nativeMidiManagerAndroid, MidiDeviceAndroid device);
     static native void nativeOnDetached(long nativeMidiManagerAndroid, MidiDeviceAndroid device);
 }