Implement WebVR presentation pausing for VR Shell Menu Mode

device/vr/vr_device_manager.cc

Index: device/vr/vr_device_manager.cc
diff --git a/device/vr/vr_device_manager.cc b/device/vr/vr_device_manager.cc
index b8c99ea3566c19e288ae011494bb6a1e7add6f04..e92ef5c17443a9fb528484b6a95499bcd92c507c 100644
--- a/device/vr/vr_device_manager.cc
+++ b/device/vr/vr_device_manager.cc
@@ -79,7 +79,7 @@ VRDevice* VRDeviceManager::GetAllowedDevice(VRServiceImpl* service,
 void VRDeviceManager::SetInstance(VRDeviceManager* instance) {
   // Unit tests can create multiple instances but only one should exist at any
   // given time so g_vr_device_manager should only go from nullptr to
-  // non-nullptr and vica versa.
+  // non-nullptr and vice versa.
   CHECK_NE(!!instance, !!g_vr_device_manager);
   g_vr_device_manager = instance;
 }
@@ -287,6 +287,31 @@ void VRDeviceManager::OnPresentEnded(VRDevice* device) {
   presenting_device_ = nullptr;
 }
 
+void VRDeviceManager::PausePresent(VRDevice* device) {
+  // Ensure the presenting device is the one that we've been requested to pause.
+  if (!presenting_device_ || presenting_device_ != device)
+    return;
+
+  // Should never have a presenting device without a presenting service.
+  DCHECK(presenting_service_);
+
+  // Notify the presenting service that it should pause.
+  presenting_service_->client()->OnPausePresent(device->id());
+}
+
+void VRDeviceManager::ResumePresent(VRDevice* device) {
+  // Ensure the presenting device is the one that we've been requested to
+  // resume.
+  if (!presenting_device_ || presenting_device_ != device)
+    return;
+
+  // Should never have a presenting device without a presenting service.
+  DCHECK(presenting_service_);
+
+  // Notify the presenting service that it should pause.
+  presenting_service_->client()->OnResumePresent(device->id());
+}
+
 void VRDeviceManager::InitializeProviders() {
   if (vr_initialized_) {
     return;