Add a snapshot of flutter/engine/src/build to our sdk

build/android/adb_run_mojo_shell

Index: build/android/adb_run_mojo_shell
diff --git a/build/android/adb_run_mojo_shell b/build/android/adb_run_mojo_shell
new file mode 100755
index 0000000000000000000000000000000000000000..b585e4a71f6f98408322161e0131c5876daae2b3
--- /dev/null
+++ b/build/android/adb_run_mojo_shell
@@ -0,0 +1,16 @@
+#!/bin/bash
+#
+# Copyright 2013 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.
+
+optional_url=$1
+parameters=$2
+
+adb logcat -c
+adb shell am start -S \
+  -a android.intent.action.VIEW \
+  -n org.chromium.mojo_shell_apk/.MojoShellActivity \
+  ${parameters:+--esa parameters "$parameters"} \
+  ${optional_url:+-d "$optional_url"}
+adb logcat -s MojoShellApplication MojoShellActivity chromium