Support sync mojo IPCs to and from bindings running on a sequence.

mojo/public/cpp/bindings/lib/sync_handle_watcher.cc

Index: mojo/public/cpp/bindings/lib/sync_handle_watcher.cc
diff --git a/mojo/public/cpp/bindings/lib/sync_handle_watcher.cc b/mojo/public/cpp/bindings/lib/sync_handle_watcher.cc
index 92b91f445272f41fd6229cc391dd544bd017217c..e4741a2eea83d1478f14dac0635d1fa98b037458 100644
--- a/mojo/public/cpp/bindings/lib/sync_handle_watcher.cc
+++ b/mojo/public/cpp/bindings/lib/sync_handle_watcher.cc
@@ -21,7 +21,7 @@ SyncHandleWatcher::SyncHandleWatcher(
       destroyed_(new base::RefCountedData<bool>(false)) {}
 
 SyncHandleWatcher::~SyncHandleWatcher() {
-  DCHECK(thread_checker_.CalledOnValidThread());
+  DCHECK(sequence_checker_.CalledOnValidSequence());
   if (registered_)
     registry_->UnregisterHandle(handle_);
 
@@ -29,12 +29,12 @@ SyncHandleWatcher::~SyncHandleWatcher() {
 }
 
 void SyncHandleWatcher::AllowWokenUpBySyncWatchOnSameThread() {
-  DCHECK(thread_checker_.CalledOnValidThread());
+  DCHECK(sequence_checker_.CalledOnValidSequence());
   IncrementRegisterCount();
 }
 
 bool SyncHandleWatcher::SyncWatch(const bool* should_stop) {
-  DCHECK(thread_checker_.CalledOnValidThread());
+  DCHECK(sequence_checker_.CalledOnValidSequence());
   IncrementRegisterCount();
   if (!registered_) {
     DecrementRegisterCount();