[Android] Add a configurable environment for devil/.

build/android/devil/env/binary_config.py

Index: build/android/devil/env/binary_config.py
diff --git a/build/android/devil/env/binary_config.py b/build/android/devil/env/binary_config.py
new file mode 100644
index 0000000000000000000000000000000000000000..7134558c60ea829740f766a63a9ab42da04b17df
--- /dev/null
+++ b/build/android/devil/env/binary_config.py
@@ -0,0 +1,18 @@
+# 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.
+
+import os
+
+from devil.env import env_config
+
+DEVIL_BINARY_DIR = 'DEVIL_BINARY_DIR'
+
+
+class BinaryConfig(env_config.EnvConfig):
+
+  @property
+  def binary_dir(self):
+    return (self._configured.get('binary_dir')
+            or os.environ.get(DEVIL_BINARY_DIR))
+