Remove third_party/golang.org/x/mobile as it is no longer used with Go 1.5.

third_party/go/src/golang.org/x/mobile/example/libhello/src/com/example/hello/MainActivity.java

Index: third_party/go/src/golang.org/x/mobile/example/libhello/src/com/example/hello/MainActivity.java
diff --git a/third_party/go/src/golang.org/x/mobile/example/libhello/src/com/example/hello/MainActivity.java b/third_party/go/src/golang.org/x/mobile/example/libhello/src/com/example/hello/MainActivity.java
deleted file mode 100644
index 61fc8b6d7254897fbc95e0c5286f06a9cfc82082..0000000000000000000000000000000000000000
--- a/third_party/go/src/golang.org/x/mobile/example/libhello/src/com/example/hello/MainActivity.java
+++ /dev/null
@@ -1,29 +0,0 @@
-/*
- * Copyright 2014 The Go 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 com.example.hello;
-
-import go.Go;
-import go.hi.Hi;
-import android.app.Activity;
-import android.os.Bundle;
-
-/*
- * MainActivity is the entry point for the libhello app.
- *
- * From here, the Go runtime is initialized and a Go function is
- * invoked via gobind language bindings.
- *
- * See example/libhello/README for details.
- */
-public class MainActivity extends Activity {
-    @Override
-    protected void onCreate(Bundle savedInstanceState) {
-        super.onCreate(savedInstanceState);
-        Go.init(getApplicationContext());
-        Hi.Hello("world");
-    }
-}