Renderer reading side of gamepad

content/browser/gamepad/gamepad_provider.cc

Index: content/browser/gamepad/gamepad_provider.cc
diff --git a/content/browser/gamepad/gamepad_provider.cc b/content/browser/gamepad/gamepad_provider.cc
index 642e2445a7bbe8fa0d0fc8fa7fd1fcbe2827c101..35b9e3f0afc398295f861e1f3c6cd697022b035d 100644
--- a/content/browser/gamepad/gamepad_provider.cc
+++ b/content/browser/gamepad/gamepad_provider.cc
@@ -119,9 +119,11 @@ void Provider::DoInitializePollingThread() {
 void Provider::DoPoll() {
   DCHECK(MessageLoop::current() == polling_thread_->message_loop());
   GamepadHardwareBuffer* hwbuf = SharedMemoryAsHardwareBuffer();
-  base::subtle::Barrier_AtomicIncrement(&hwbuf->start_marker, 1);
+  // Acquire the SeqLock. There is only ever one writer to this data.
+  // See gamepad_hardware_buffer.h.
+  hwbuf->sequence.WriteBegin();
   data_fetcher_->GetGamepadData(&hwbuf->buffer, devices_changed_);
-  base::subtle::Barrier_AtomicIncrement(&hwbuf->end_marker, 1);
+  hwbuf->sequence.WriteEnd();
   devices_changed_ = false;
   // Schedule our next interval of polling.
   ScheduleDoPoll();