Provide WebVR pose data only to the focused frame.

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

Index: third_party/WebKit/Source/modules/vr/VRDisplay.h
diff --git a/third_party/WebKit/Source/modules/vr/VRDisplay.h b/third_party/WebKit/Source/modules/vr/VRDisplay.h
index c75631438803f8eea31a36b2196ff535f4d52939..1a2e583d6cb702fb5da63a73c31adc90efc5dede 100644
--- a/third_party/WebKit/Source/modules/vr/VRDisplay.h
+++ b/third_party/WebKit/Source/modules/vr/VRDisplay.h
@@ -92,6 +92,8 @@ class VRDisplay final : public EventTargetWithInlineData,
   // ScriptWrappable implementation.
   bool hasPendingActivity() const final;
 
+  void focusChanged(bool focused);
+
   DECLARE_VIRTUAL_TRACE();
 
  protected:
@@ -148,7 +150,7 @@ class VRDisplay final : public EventTargetWithInlineData,
   Member<VREyeParameters> m_eyeParametersLeft;
   Member<VREyeParameters> m_eyeParametersRight;
   device::mojom::blink::VRPosePtr m_framePose;
-  int16_t m_frameId;
+  int16_t m_frameId = -1;
   VRLayer m_layer;
   double m_depthNear = 0.01;
   double m_depthFar = 10000.0;
@@ -167,6 +169,7 @@ class VRDisplay final : public EventTargetWithInlineData,
   bool m_displayBlurred = false;
   bool m_reenteredFullscreen = false;
   double m_timebase = -1;
+  bool m_focused = false;
 
   device::mojom::blink::VRDisplayPtr m_display;