Add Android-backend to the memory_inspector (prerequisites).

tools/memory_inspector/tests/mock_adb/mock_adb.py

Index: tools/memory_inspector/tests/mock_adb/mock_adb.py
diff --git a/tools/memory_inspector/tests/mock_adb/mock_adb.py b/tools/memory_inspector/tests/mock_adb/mock_adb.py
new file mode 100644
index 0000000000000000000000000000000000000000..dc8eee230e013016aef2b3b88a1347ca28185f23
--- /dev/null
+++ b/tools/memory_inspector/tests/mock_adb/mock_adb.py
@@ -0,0 +1,36 @@
+# Copyright 2014 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.
+
+import json
+import os
+import tempfile
+
+
+class MockAdb(object):
+  """Simple and effective mock for Android adb.
+
+  This module is meant to be used in integration tests in conjunction with the
+  other script named 'adb' living in the same directory.
+  Essentially this class is used prepare a dictionary of mocked responses to adb

[Philippe, 2014/02/10 16:41:03]

Nit: s/prepare/prepare to

[Primiano Tucci (use gerrit), 2014/02/11 12:10:51]

Done.

+  commands. The dictionary is stored into a json file and read by the mock 'adb'
+  script at each invocation. The path of the json dict is held in MOCK_ADB_CFG.
+  """
+
+  def __init__(self):
+    self._responses = {}  # Maps expected_cmd (str) -> prepared_response (str).
+    self._cfg_file = None
+
+  def Start(self):
+    (fd_num, self._cfg_file) = tempfile.mkstemp()
+    with os.fdopen(fd_num, 'w') as f:
+      json.dump(self._responses, f)
+      f.close()

[Philippe, 2014/02/10 16:41:03]

Nit: not sure this line is needed with the 'with' statement. I'm not the expert
here though :)

[Primiano Tucci (use gerrit), 2014/02/11 12:10:51]

I found this in some code snippets. I'm afraid that the rationale is that
os.fdopen behaves differently from open().
Not 100% sure (might be just the snippets were wrong). However I prefer to be
paranoid rather than risking of leaking a fd :)

+    os.environ['MOCK_ADB_CFG'] = self._cfg_file
+
+  def Stop(self):
+    assert(self._cfg_file), 'Stop called before Start.'
+    os.unlink(self._cfg_file)
+
+  def PrepareResponse(self, cmd, response):
+    self._responses[cmd] = response