Fix reenter webvr presentation on Windows after exiting.

We were getting into a state where we thought we had requested a vsync
from the device, but actually haven't.  This causes future RAFs to not
run, and we won't render.

BUG=835888

Change-Id: I41af90675fa5ba8e6b78a598594f4a2cf28217ed
Reviewed-on: https://chromium-review.googlesource.com/1028935Reviewed-by: Bill Orr <billorr@chromium.org>
Reviewed-by: Klaus Weidner <klausw@chromium.org>
Commit-Queue: Bill Orr <billorr@chromium.org>
Cr-Commit-Position: refs/heads/master@{#553888}

device/vr/oculus/oculus_render_loop.cc

@@ -228,6 +228,8 @@ void OculusRenderLoop::RequestPresent(
 
 void OculusRenderLoop::ExitPresent() {
   is_presenting_ = false;
+  binding_.Close();
+  submit_client_ = nullptr;
 }
 
 void OculusRenderLoop::Init() {}

device/vr/openvr/openvr_render_loop.cc

@@ -195,6 +195,8 @@ void OpenVRRenderLoop::RequestPresent(
 void OpenVRRenderLoop::ExitPresent() {
   is_presenting_ = false;
   report_webxr_input_ = false;
+  binding_.Close();
+  submit_client_ = nullptr;
   vr_compositor_->SuspendRendering(true);
 }
 

third_party/blink/renderer/modules/vr/vr_display.cc

@@ -471,6 +471,10 @@ ScriptPromise VRDisplay::requestPresent(ScriptState* script_state,
         WTF::Bind(&VRDisplay::OnPresentationProviderConnectionError,
                   WrapWeakPersistent(this)));
     pending_present_request_ = true;
+
+    // The old vr_presentation_provider_ won't be delivering any vsyncs anymore,
+    // so we aren't waiting on it anymore.
+    pending_presenting_vsync_ = false;
   } else {
     UpdateLayerBounds();
     resolver->Resolve();