[pylib/devil] Create devil.android.base_tool and derive valgrind_tools classes from it

build/android/devil/android/valgrind_tools/__init__.py

Index: build/android/devil/android/valgrind_tools/__init__.py
diff --git a/build/android/devil/android/valgrind_tools/__init__.py b/build/android/devil/android/valgrind_tools/__init__.py
new file mode 100644
index 0000000000000000000000000000000000000000..0182d4c17644e2f017c67fec8a10b498fc2049c2
--- /dev/null
+++ b/build/android/devil/android/valgrind_tools/__init__.py
@@ -0,0 +1,21 @@
+# Copyright (c) 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.
+"""
+Classes in this package define additional actions that need to be taken to run a
+test under some kind of runtime error detection tool.
+
+The interface is intended to be used as follows.
+
+1. For tests that simply run a native process (i.e. no activity is spawned):
+
+Call tool.CopyFiles(device).
+Prepend test command line with tool.GetTestWrapper().
+
+2. For tests that spawn an activity:
+
+Call tool.CopyFiles(device).
+Call tool.SetupEnvironment().
+Run the test as usual.
+Call tool.CleanUpEnvironment().
+"""