Workaround for UCRT deadlock between gpu's main and watchdog threads

gpu/ipc/service/gpu_init.cc

 // 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.
 
 #include "gpu/ipc/service/gpu_init.h"
 
 #include "base/command_line.h"
 #include "base/metrics/histogram_macros.h"
 #include "base/strings/string_number_conversions.h"
 #include "base/third_party/dynamic_annotations/dynamic_annotations.h"
@@ skipping 145 matching lines @@
   bool delayed_watchdog_enable = false;
 
 #if defined(OS_CHROMEOS)
   // Don't start watchdog immediately, to allow developers to switch to VT2 on
   // startup.
   delayed_watchdog_enable = true;
 #endif
 
   // Start the GPU watchdog only after anything that is expected to be time
   // consuming has completed, otherwise the process is liable to be aborted.
-  if (enable_watchdog && !delayed_watchdog_enable)
+  if (enable_watchdog && !delayed_watchdog_enable) {
     watchdog_thread_ = gpu::GpuWatchdogThread::Create();
+#if defined(OS_WIN)
+    // This is a workaround for an occasional deadlock between watchdog and
+    // current thread. Watchdog hangs at thread initialization in
+    // __acrt_thread_attach() and current thread in std::setlocale(...)
+    // (during InitializeGLOneOff()). Source of the deadlock looks like an old
+    // UCRT bug that was supposed to be fixed in 10.0.10586 release of UCRT,
+    // but we might have come accross a not-yet-covered scenario.

[Ken Russell (switch to Gerrit), 2017/05/04 17:18:48]

Please refer to crbug.com/718388 in the comment, in case this code's later
changed in bulk and git blame doesn't find it easily.

+    // References:
+    // https://bugs.python.org/issue26624
+    // http://stackoverflow.com/questions/35572792/setlocale-stuck-on-windows
+    auto watchdog_started = watchdog_thread_->WaitUntilThreadStarted();
+    DCHECK(watchdog_started);
+#endif  // OS_WIN
+  }
 
   // Get vendor_id, device_id, driver_version from browser process through
   // commandline switches.
   GetGpuInfoFromCommandLine(gpu_info_, command_line);
 #if defined(OS_LINUX) && !defined(OS_CHROMEOS)
   if (gpu_info_.gpu.vendor_id == 0x10de &&  // NVIDIA
       gpu_info_.driver_vendor == "NVIDIA" && !CanAccessNvidiaDeviceFile())
     return false;
 #endif
   gpu_info_.in_process_gpu = false;
@@ skipping 86 matching lines @@
 
   if (!gpu_info_.sandboxed && !attempted_startsandbox) {
     gpu_info_.sandboxed =
         sandbox_helper_->EnsureSandboxInitialized(watchdog_thread_.get());
   }
 
   return true;
 }
 
 }  // namespace gpu