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

build/android/adb_gdb_cronet_sample

Index: build/android/adb_gdb_cronet_sample
diff --git a/build/android/adb_gdb_cronet_sample b/build/android/adb_gdb_cronet_sample
new file mode 100755
index 0000000000000000000000000000000000000000..8d0c864d1332ada23b576f850bb48fae34f38835
--- /dev/null
+++ b/build/android/adb_gdb_cronet_sample
@@ -0,0 +1,16 @@
+#!/bin/bash
+#
+# Copyright 2014 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.
+#
+# Attach to or start a ContentShell process and debug it.
+# See --help for details.
+#
+PROGDIR=$(dirname "$0")
+export ADB_GDB_PROGNAME=$(basename "$0")
+export ADB_GDB_ACTIVITY=.CronetSampleActivity
+"$PROGDIR"/adb_gdb \
+    --program-name=CronetSample \
+    --package-name=org.chromium.cronet_sample_apk \
+    "$@"