WebVR: lock focus while presenting to presenting window

third_party/WebKit/Source/modules/vr/VRDisplay.cpp

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "modules/vr/VRDisplay.h"
 
 #include "core/css/StylePropertySet.h"
 #include "core/dom/DOMException.h"
 #include "core/dom/FrameRequestCallback.h"
 #include "core/dom/ScriptedAnimationController.h"
@@ skipping 87 matching lines @@
   } else {
     stage_parameters_ = nullptr;
   }
 
   if (need_on_present_change) {
     OnPresentChange();
   }
 }
 
 bool VRDisplay::getFrameData(VRFrameData* frame_data) {
-  if (!navigator_vr_->IsFocused() || !frame_pose_ || display_blurred_)
+  if (!FocusedOrPresenting() || !frame_pose_ || display_blurred_)
     return false;
 
   if (!frame_data)
     return false;
 
   if (depth_near_ == depth_far_)
     return false;
 
   return frame_data->Update(frame_pose_, eye_parameters_left_,
                             eye_parameters_right_, depth_near_, depth_far_);
@@ skipping 433 matching lines @@
     }
   }
 
   RefPtr<Image> image_ref = rendering_context_->GetImage(
       kPreferAcceleration, kSnapshotReasonCreateImageBitmap);
 
   // Hardware-accelerated rendering should always be texture backed,
   // as implemented by AcceleratedStaticBitmapImage. Ensure this is
   // the case, don't attempt to render if using an unexpected drawing
   // path.
-  if (!image_ref->IsTextureBacked()) {
+  if (!image_ref.Get() || !image_ref->IsTextureBacked()) {

[klausw, 2017/05/03 16:20:42]

Is this out of paranoia, or have you run into cases where this was null? If the
latter, may be preferable to make a separate change for this to avoid losing
that fix in case this one gets rolled back.

[mthiesse, 2017/05/04 17:29:01]

I was running into this occasionally when using the under neon lights webVR
demo, like 30 seconds into running it. Possibly a memory issue, possibly not,
but either way we shouldn't crash. Will fix this in a separate CL.

     NOTREACHED() << "WebVR requires hardware-accelerated rendering to texture";
     return;
   }
 
   // The AcceleratedStaticBitmapImage must be kept alive until the
   // mailbox is used via createAndConsumeTextureCHROMIUM, the mailbox
   // itself does not keep it alive. We must keep a reference to the
   // image until the mailbox was consumed.
   StaticBitmapImage* static_image =
       static_cast<StaticBitmapImage*>(image_ref.Get());
@@ skipping 214 matching lines @@
   // this is due to WaitForIncomingMethodCall receiving the OnVSync
   // but queueing it for immediate execution since it doesn't match
   // the interface being waited on.
   Platform::Current()->CurrentThread()->GetWebTaskRunner()->PostTask(
       BLINK_FROM_HERE,
       WTF::Bind(&VRDisplay::ProcessScheduledAnimations,
                 WrapWeakPersistent(this), timebase_ + time_delta.InSecondsF()));
 }
 
 void VRDisplay::ConnectVSyncProvider() {
-  if (!navigator_vr_->IsFocused() || vr_v_sync_provider_.is_bound())
+  if (!FocusedOrPresenting() || vr_v_sync_provider_.is_bound())
     return;
   display_->GetVRVSyncProvider(mojo::MakeRequest(&vr_v_sync_provider_));
   vr_v_sync_provider_.set_connection_error_handler(ConvertToBaseCallback(
       WTF::Bind(&VRDisplay::OnVSyncConnectionError, WrapWeakPersistent(this))));
   if (pending_vrdisplay_raf_ && !display_blurred_) {
     pending_vsync_ = true;
     vr_v_sync_provider_->GetVSync(ConvertToBaseCallback(
         WTF::Bind(&VRDisplay::OnVSync, WrapWeakPersistent(this))));
   }
 }
@@ skipping 38 matching lines @@
   return GetExecutionContext() && HasEventListeners();
 }
 
 void VRDisplay::FocusChanged() {
   // TODO(mthiesse): Blur/focus the display.
   DVLOG(1) << __FUNCTION__;
   vr_v_sync_provider_.reset();
   ConnectVSyncProvider();
 }
 
+bool VRDisplay::FocusedOrPresenting() {
+  // TODO(mthiesse, crbug.com/687411): Focused state should be determined
+  // browser-side to correctly track which display should be receiving input.
+  return navigator_vr_->IsFocused() || is_presenting_;
+}
+
 DEFINE_TRACE(VRDisplay) {
   EventTargetWithInlineData::Trace(visitor);
   ContextLifecycleObserver::Trace(visitor);
   visitor->Trace(navigator_vr_);
   visitor->Trace(capabilities_);
   visitor->Trace(stage_parameters_);
   visitor->Trace(eye_parameters_left_);
   visitor->Trace(eye_parameters_right_);
   visitor->Trace(layer_);
   visitor->Trace(rendering_context_);
   visitor->Trace(scripted_animation_controller_);
   visitor->Trace(pending_present_resolvers_);
 }
 
 }  // namespace blink