Provide WebVR pose data only to the focused frame.

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

 // Copyright 2015 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/VRController.h"
 
 #include "bindings/core/v8/ScriptPromiseResolver.h"
 #include "core/dom/DOMException.h"
 #include "core/dom/Document.h"
 #include "core/frame/LocalFrame.h"
@@ skipping 46 matching lines @@
 // here. Upon calling SetClient in the constructor we should receive one call
 // for each VRDisplay that was already connected at the time.
 void VRController::OnDisplayConnected(
     device::mojom::blink::VRDisplayPtr display,
     device::mojom::blink::VRDisplayClientRequest request,
     device::mojom::blink::VRDisplayInfoPtr displayInfo) {
   VRDisplay* vrDisplay =
       new VRDisplay(m_navigatorVR, std::move(display), std::move(request));
   vrDisplay->update(displayInfo);
   vrDisplay->onConnected();
+  vrDisplay->focusChanged(m_focused);
   m_displays.push_back(vrDisplay);
 
   if (m_displays.size() == m_numberOfSyncedDisplays) {
     m_displaySynced = true;
     onGetDisplays();
   }
 }
 
+void VRController::focusChanged(bool focused) {
+  m_focused = focused;
+  for (size_t i = 0; i < m_displays.size(); ++i)

[jbroman, 2017/02/02 16:07:20]

super-nit: you could use a range-based loop here too:

for (const auto& display : m_displays)
  display->focusChanged(focused);

[mthiesse, 2017/02/02 17:52:18]

Done.

+    m_displays[i]->focusChanged(focused);
+}
+
 // Called when the VRService has called OnDisplayConnected for all active
 // VRDisplays.
 void VRController::onDisplaysSynced(unsigned numberOfDisplays) {
   m_numberOfSyncedDisplays = numberOfDisplays;
   if (m_numberOfSyncedDisplays == m_displays.size()) {
     m_displaySynced = true;
     onGetDisplays();
   }
 }
 
@@ skipping 26 matching lines @@
 }
 
 DEFINE_TRACE(VRController) {
   visitor->trace(m_navigatorVR);
   visitor->trace(m_displays);
 
   ContextLifecycleObserver::trace(visitor);
 }
 
 }  // namespace blink