android: Point EMULATOR_SDK_ROOT to a location inside the repository.

build/android/avd.py

Index: build/android/avd.py
diff --git a/build/android/avd.py b/build/android/avd.py
index 2685c592bedf4d4f276169a99741b3d374f6d377..76107651f3378e1f7776036663d0b91986985691 100755
--- a/build/android/avd.py
+++ b/build/android/avd.py
@@ -23,9 +23,7 @@ from pylib.utils import emulator
 def main(argv):
   # ANDROID_SDK_ROOT needs to be set to the location of the SDK used to launch
   # the emulator to find the system images upon launch.
-  emulator_sdk = os.path.join(constants.EMULATOR_SDK_ROOT,
-                              'android_tools', 'sdk')
-  os.environ['ANDROID_SDK_ROOT'] = emulator_sdk
+  os.environ['ANDROID_SDK_ROOT'] = constants.ANDROID_SDK_ROOT
 
   opt_parser = optparse.OptionParser(description='AVD script.')
   opt_parser.add_option('-n', '--num', dest='emulator_count',