Provide WebVR pose data only to the focused frame.

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

Index: third_party/WebKit/Source/modules/vr/VRDisplay.cpp
diff --git a/third_party/WebKit/Source/modules/vr/VRDisplay.cpp b/third_party/WebKit/Source/modules/vr/VRDisplay.cpp
index 4810e4fa6c24817abeabd72c20f1899c1dfaa14f..01d251cd648319737abfb370e3ed2f04d07819f2 100644
--- a/third_party/WebKit/Source/modules/vr/VRDisplay.cpp
+++ b/third_party/WebKit/Source/modules/vr/VRDisplay.cpp
@@ -114,7 +114,7 @@ void VRDisplay::disconnected() {
 }
 
 bool VRDisplay::getFrameData(VRFrameData* frameData) {
-  if (!m_framePose || m_displayBlurred)
+  if (!m_navigatorVR->isFocused() || !m_framePose || m_displayBlurred)
     return false;
 
   if (!frameData)
@@ -128,7 +128,7 @@ bool VRDisplay::getFrameData(VRFrameData* frameData) {
 }
 
 VRPose* VRDisplay::getPose() {
-  if (!m_framePose || m_displayBlurred)
+  if (!m_navigatorVR->isFocused() || !m_framePose || m_displayBlurred)
     return nullptr;
 
   VRPose* pose = VRPose::create();
@@ -672,6 +672,8 @@ void VRDisplay::OnVSync(device::mojom::blink::VRPosePtr pose,
 }
 
 void VRDisplay::ConnectVSyncProvider() {
+  if (!m_navigatorVR->isFocused())
+    return;
   m_display->GetVRVSyncProvider(mojo::MakeRequest(&m_vrVSyncProvider));
   if (m_pendingRaf && !m_displayBlurred) {
     m_vrVSyncProvider->GetVSync(convertToBaseCallback(
@@ -747,6 +749,14 @@ bool VRDisplay::hasPendingActivity() const {
   return getExecutionContext() && hasEventListeners();
 }
 
+void VRDisplay::focusChanged() {
+  // TODO(mthiesse): Blur/focus the display.
+  m_vrVSyncProvider.reset();
+  if (m_navigatorVR->isFocused()) {

[jbroman, 2017/02/06 15:34:18]

nit: This check seems redundant with the one in ConnectVSyncProvider. Is it
useful to check twice?

[mthiesse, 2017/02/06 16:37:47]

Removed redundant check.

+    ConnectVSyncProvider();
+  }
+}
+
 DEFINE_TRACE(VRDisplay) {
   EventTargetWithInlineData::trace(visitor);
   ContextLifecycleObserver::trace(visitor);