[Android] Allow gtests to pull app data off the device before clearing it.

build/android/pylib/device/device_utils.py

Index: build/android/pylib/device/device_utils.py
diff --git a/build/android/pylib/device/device_utils.py b/build/android/pylib/device/device_utils.py
index c8b471831e62aec343c705afb12bd3095bd8ea24..f5f74890540df17d2630ef0c8f3b813bddcb881f 100644
--- a/build/android/pylib/device/device_utils.py
+++ b/build/android/pylib/device/device_utils.py
@@ -364,6 +364,28 @@ class DeviceUtils(object):
     return output[len('package:'):]
 
   @decorators.WithTimeoutAndRetriesFromInstance()
+  def GetApplicationDataDirectory(self, package, timeout=None, retries=None):
+    """Get the data directory on the device for the given package.
+
+    Args:
+      package: Name of the package.
+
+    Returns:
+      The package's data directory, or None if the package doesn't exist on the
+      device.
+    """
+    try:
+      output = self._RunPipedShellCommand(
+          'pm dump %s | grep dataDir=' % cmd_helper.SingleQuote(package))
+      for line in output:
+        _, _, dataDir = line.partition('dataDir=')
+        if dataDir:
+          return dataDir
+    except device_errors.CommandFailedError:
+      logging.exception('Could not find data directory for %s', package)
+    return None
+
+  @decorators.WithTimeoutAndRetriesFromInstance()
   def WaitUntilFullyBooted(self, wifi=False, timeout=None, retries=None):
     """Wait for the device to fully boot.