Prevent browser crash resulting from misbehaving WebVR renderer requesting multiple VSyncs.

chrome/browser/android/vr_shell/non_presenting_gvr_delegate.cc

Index: chrome/browser/android/vr_shell/non_presenting_gvr_delegate.cc
diff --git a/chrome/browser/android/vr_shell/non_presenting_gvr_delegate.cc b/chrome/browser/android/vr_shell/non_presenting_gvr_delegate.cc
index 2e69283b77756ce329c1810f4350599111a2e4c3..736e187307295eacc9e6b4e85aa3a5bd34dc88dc 100644
--- a/chrome/browser/android/vr_shell/non_presenting_gvr_delegate.cc
+++ b/chrome/browser/android/vr_shell/non_presenting_gvr_delegate.cc
@@ -61,7 +61,9 @@ NonPresentingGvrDelegate::OnSwitchToPresentingDelegate() {
 void NonPresentingGvrDelegate::StopVSyncLoop() {
   vsync_task_.Cancel();
   if (!callback_.is_null()) {
-    base::ResetAndReturn(&callback_).Run(nullptr, base::TimeDelta(), -1);
+    base::ResetAndReturn(&callback_)
+        .Run(nullptr, base::TimeDelta(), -1,
+             device::mojom::VRVSyncProvider::Error::ERROR_TRY_AGAIN);
   }
   gvr_api_->PauseTracking();
   // If the loop is stopped, it's not considered to be paused.
@@ -110,6 +112,8 @@ void NonPresentingGvrDelegate::GetVSync(const GetVSyncCallback& callback) {
     if (!callback_.is_null()) {
       mojo::ReportBadMessage("Requested VSync before waiting for response to "
           "previous request.");
+      callback.Run(nullptr, base::TimeDelta(), -1,
+                   device::mojom::VRVSyncProvider::Error::ERROR_BAD_REQUEST);
       return;
     }
     callback_ = callback;
@@ -134,7 +138,8 @@ void NonPresentingGvrDelegate::SendVSync(base::TimeDelta time,
 
   gvr::Mat4f head_mat = gvr_api_->ApplyNeckModel(
       gvr_api_->GetHeadSpaceFromStartSpaceRotation(target_time), 1.0f);
-  callback.Run(VrShell::VRPosePtrFromGvrPose(head_mat), time, -1);
+  callback.Run(VrShell::VRPosePtrFromGvrPose(head_mat), time, -1,
+               device::mojom::VRVSyncProvider::Error::ERROR_NONE);
 }
 
 bool NonPresentingGvrDelegate::SupportsPresentation() {