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

build/android/devil/android/sdk/fastboot.py

Index: build/android/devil/android/sdk/fastboot.py
diff --git a/build/android/devil/android/sdk/fastboot.py b/build/android/devil/android/sdk/fastboot.py
index cfc566a67c292f8ee2e9f4d0d2df5bdf774acea8..aebff203fdaa602d00087f04aebd5f8328da3d62 100644
--- a/build/android/devil/android/sdk/fastboot.py
+++ b/build/android/devil/android/sdk/fastboot.py
@@ -11,19 +11,21 @@ should be delegated to a higher level (ex. FastbootUtils).
 
 import os
 
+from devil import devil_env
 from devil.android import decorators
 from devil.android import device_errors
 from devil.utils import cmd_helper
-from pylib import constants
+from devil.utils import lazy
 
-_FASTBOOT_CMD = os.path.join(
-    constants.ANDROID_SDK_ROOT, 'platform-tools', 'fastboot')
 _DEFAULT_TIMEOUT = 30
 _DEFAULT_RETRIES = 3
 _FLASH_TIMEOUT = _DEFAULT_TIMEOUT * 10
 
 class Fastboot(object):
 
+  _fastboot_path = lazy.WeakConstant(lambda: os.path.join(
+      devil_env.config.LocalPath('android_sdk'), 'platform-tools', 'adb'))
+
   def __init__(self, device_serial, default_timeout=_DEFAULT_TIMEOUT,
                default_retries=_DEFAULT_RETRIES):
     """Initializes the FastbootWrapper.
@@ -51,7 +53,7 @@ class Fastboot(object):
       TypeError: If cmd is not of type list.
     """
     if type(cmd) == list:
-      cmd = [_FASTBOOT_CMD, '-s', self._device_serial] + cmd
+      cmd = [self._fastboot_path.read(), '-s', self._device_serial] + cmd
     else:
       raise TypeError(
           'Command for _RunFastbootCommand must be a list.')