[Android] Dedup content_browsertests test setup from gtests.

build/android/pylib/android_commands.py

Index: build/android/pylib/android_commands.py
diff --git a/build/android/pylib/android_commands.py b/build/android/pylib/android_commands.py
index 73d0c2fb50adf2acfcff6c7d82feee06f4d6fbc8..4cf070d0711a9626edf1ba6eae35efe0f7bb7e40 100644
--- a/build/android/pylib/android_commands.py
+++ b/build/android/pylib/android_commands.py
@@ -262,6 +262,10 @@ class AndroidCommands(object):
     """Returns our AdbInterface to avoid us wrapping all its methods."""
     return self._adb
 
+  def GetDevice(self):
+    """Returns the device serial."""
+    return self._device
+
   def IsOnline(self):
     """Checks whether the device is online.