Force events to be non blocking if main thread is unresponsive.

device/base/synchronization/one_writer_seqlock.cc

Index: device/base/synchronization/one_writer_seqlock.cc
diff --git a/device/base/synchronization/one_writer_seqlock.cc b/device/base/synchronization/one_writer_seqlock.cc
index 7b855cfd1cb4c79c464527cd71436ae23c470bcb..b0eb3810dd4e291bedb72feeb2a49ddee698df25 100644
--- a/device/base/synchronization/one_writer_seqlock.cc
+++ b/device/base/synchronization/one_writer_seqlock.cc
@@ -24,6 +24,17 @@ base::subtle::Atomic32 OneWriterSeqLock::ReadBegin() const {
   return version;
 }
 
+void OneWriterSeqLock::TryRead(bool* can_read,
+                               base::subtle::Atomic32* version) const {
+  DCHECK(can_read);
+  DCHECK(version);
+
+  *version = base::subtle::NoBarrier_Load(&sequence_);
+  // If the counter is even, then the associated data might be in a
+  // consistent state, so we can try to read.
+  *can_read = (*version & 1) == 0;
+}
+
 bool OneWriterSeqLock::ReadRetry(base::subtle::Atomic32 version) const {
   // If the sequence number was updated then a read should be re-attempted.
   // -- Load fence, read membarrier