[Android] Print the stack of deadlocked threads when sharding.

build/android/pylib/utils/watchdog_timer.py

Index: build/android/pylib/utils/watchdog_timer.py
diff --git a/build/android/pylib/utils/watchdog_timer.py b/build/android/pylib/utils/watchdog_timer.py
new file mode 100644
index 0000000000000000000000000000000000000000..d14dabb4dd7800eb1883fc7aae8cdc2b8f4a538f
--- /dev/null
+++ b/build/android/pylib/utils/watchdog_timer.py
@@ -0,0 +1,37 @@
+# Copyright 2013 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.
+
+"""WatchdogTimer timeout objects."""
+
+import time
+
+
+class WatchdogTimer(object):
+  """A resetable timeout-based watchdog.
+
+  This object is threadsafe.
+  """
+
+  def __init__(self, timeout):
+    """Initializes the watchdog.
+
+    Args:
+      timeout: The timeout in seconds. If timeout is None it will never timeout.
+    """
+    self._start_time = time.time()
+    self._timeout = timeout
+
+  def Reset(self):
+    """Resets the timeout countdown."""
+    self._start_time = time.time()
+
+  def IsTimedOut(self):
+    """Whether the watchdog has timed out.
+
+    Returns:
+      True if the watchdog has timed out, False otherwise.
+    """
+    if self._timeout is None:
+      return False
+    return time.time() - self._start_time > self._timeout