Identify the hung thread using the Wait Chain Traversal API

base/win/wait_chain.h

Index: base/win/wait_chain.h
diff --git a/base/win/wait_chain.h b/base/win/wait_chain.h
new file mode 100644
index 0000000000000000000000000000000000000000..49d920584e220f891d8d83c2ddcb64d9de46bd90
--- /dev/null
+++ b/base/win/wait_chain.h
@@ -0,0 +1,34 @@
+// Copyright 2016 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.
+
+#ifndef BASE_WIN_WAIT_CHAIN_H_
+#define BASE_WIN_WAIT_CHAIN_H_
+
+#include <windows.h>
+#include <wct.h>
+
+#include <vector>
+
+namespace base {
+namespace win {
+
+using WaitChain = std::vector<WAITCHAIN_NODE_INFO>;

[grt (UTC plus 2), 2016/04/12 14:31:12]

consider WaitChainNodeInfoVector or WaitChainNodeVector or something. this makes
the use of the type in chrome_watcher_main.cc more obvious. when first looking
at it, it wasn't clear what the reverse iterator was iterating over. by putting
"Vector" in the type name, it's a little more clear.

[Patrick Monette, 2016/04/12 19:13:00]

Done.

+
+// Get the wait chain for the |thread_id|. Also specifies if the |wait_chain|

[grt (UTC plus 2), 2016/04/12 14:31:12]

nit: "Gets the wait chain for |thread_id|."

[Patrick Monette, 2016/04/12 19:13:00]

Done.

+// contains a deadlock. Returns true on success.
+//
+// From MSDN: A wait chain is an alternating sequence of threads and
+// synchronization objects; each thread waits for the object that follows it,
+// which is owned by the subsequent thread in the chain.
+bool GetThreadWaitChain(DWORD thread_id,
+                        WaitChain* wait_chain,
+                        bool* is_deadlock);
+
+// Returns a string that represents the node for a wait chain.
+std::wstring WaitChainNodeToString(const WAITCHAIN_NODE_INFO& node);
+
+}  // namespace win
+}  // namespace base
+
+#endif  // BASE_WIN_WAIT_CHAIN_H_