[Android] Add a configurable environment for devil/. (RELAND 2)

build/android/devil/android/sdk/build_tools.py

Index: build/android/devil/android/sdk/build_tools.py
diff --git a/build/android/devil/android/sdk/build_tools.py b/build/android/devil/android/sdk/build_tools.py
new file mode 100644
index 0000000000000000000000000000000000000000..6965dd43547ead9d2ff6dc789b73340c30d75cc4
--- /dev/null
+++ b/build/android/devil/android/sdk/build_tools.py
@@ -0,0 +1,51 @@
+# 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 import devil_env
+from devil.utils import lazy
+
+with devil_env.SysPath(devil_env.CATAPULT_BASE_PATH):
+  from catapult_base import dependency_manager # pylint: disable=import-error
+
+
+def GetPath(build_tool):
+  try:
+    return devil_env.config.LocalPath(build_tool)
+  except dependency_manager.NoPathFoundError:
+    pass
+
+  try:
+    return _PathInLocalSdk(build_tool)
+  except dependency_manager.NoPathFoundError:
+    pass
+
+  return devil_env.config.FetchPath(build_tool)
+
+
+def _PathInLocalSdk(build_tool):
+  build_tools_path = _build_tools_path.read()
+  return (os.path.join(build_tools_path, build_tool) if build_tools_path
+          else None)
+
+
+def _FindBuildTools():
+  android_sdk_path = devil_env.config.LocalPath('android_sdk')
+  if not android_sdk_path:
+    return None
+
+  build_tools_contents = os.listdir(
+      os.path.join(android_sdk_path, 'build-tools'))
+
+  if not build_tools_contents:
+    return None
+  else:
+    if len(build_tools_contents) > 1:
+      build_tools_contents.sort()
+    return os.path.join(android_sdk_path, 'build-tools',
+                        build_tools_contents[-1])
+
+
+_build_tools_path = lazy.WeakConstant(_FindBuildTools)