Provide WebVR pose data only to the focused frame.

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

Index: third_party/WebKit/Source/modules/vr/NavigatorVR.cpp
diff --git a/third_party/WebKit/Source/modules/vr/NavigatorVR.cpp b/third_party/WebKit/Source/modules/vr/NavigatorVR.cpp
index c29f8405d094d66596dc02b21e17045db4c89ae0..11bae92a6288a7673326addf76704f4dbc526e47 100644
--- a/third_party/WebKit/Source/modules/vr/NavigatorVR.cpp
+++ b/third_party/WebKit/Source/modules/vr/NavigatorVR.cpp
@@ -13,6 +13,7 @@
 #include "core/frame/LocalFrame.h"
 #include "core/frame/Navigator.h"
 #include "core/frame/UseCounter.h"
+#include "core/page/FocusController.h"
 #include "core/page/Page.h"
 #include "modules/vr/VRController.h"
 #include "modules/vr/VRDisplay.h"
@@ -76,6 +77,8 @@ VRController* NavigatorVR::controller() {
 
   if (!m_controller) {
     m_controller = new VRController(this);
+    m_controller->setListeningForActivate(m_listeningForActivate);
+    m_controller->focusChanged(m_focused);
   }
 
   return m_controller;
@@ -89,13 +92,14 @@ Document* NavigatorVR::document() {
 DEFINE_TRACE(NavigatorVR) {
   visitor->trace(m_controller);
   Supplement<Navigator>::trace(visitor);
-  PageVisibilityObserver::trace(visitor);
 }
 
 NavigatorVR::NavigatorVR(Navigator& navigator)
-    : Supplement<Navigator>(navigator),
-      PageVisibilityObserver(navigator.frame()->page()) {
+    : Supplement<Navigator>(navigator) {
   navigator.frame()->domWindow()->registerEventListenerObserver(this);
+  navigator.frame()->page()->focusController().registerFocusChangedObserver(
+      this);
+  focusedFrameChanged();
 }
 
 NavigatorVR::~NavigatorVR() {}
@@ -121,19 +125,30 @@ void NavigatorVR::dispatchVRGestureEvent(VRDisplayEvent* event) {
   window->dispatchEvent(event);
 }
 
-void NavigatorVR::pageVisibilityChanged() {
-  if (!page())
+void NavigatorVR::focusedFrameChanged() {

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

nit: This condition might be clearer factored out to a static function?

static bool isFrameDocumentFocused(LocalFrame* frame) {
  if (!frame) return false;
  Page* page = frame->page();
  Document* document = frame->document();
  return page && document &&
page->focusController().isDocumentFocused(document);
}

void NavigatorVR::focusedFrameChanged() {
  const bool focused = supplementable() &&
isFrameDocumentFocused(supplementable()->frame());
  if (m_focused != focused && m_controller) {
    m_controller->setListeningForActivate(focused && m_listeningForActivate);
    m_controller->focusChanged(focused);
  }
  m_focused = focused;
}

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

Done.

+  if (supplementable() && supplementable()->frame() &&
+      supplementable()->frame()->page() &&
+      supplementable()->frame()->document() &&
+      supplementable()->frame()->page()->focusController().isDocumentFocused(

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

Do you really want isDocumentFocused? This will return true if any descendant
frame has focus as well. This may or may not be what you want, but you probably
want to match whatever you'll implement on the browser side later on.

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

Hmm I think you're right, and isDocumentFocused was probably only working by
fluke since we only allow one VSync provider to be connected at a time.

+          *supplementable()->frame()->document())) {
+    if (!m_focused && m_controller) {
+      m_controller->setListeningForActivate(m_listeningForActivate);
+      m_controller->focusChanged(true);
+    }
+    m_focused = true;
     return;
-  if (m_controller) {
-    m_controller->setListeningForActivate(page()->isPageVisible() &&
-                                          m_listeningForActivate);
   }
+  if (m_focused && m_controller) {
+    m_controller->setListeningForActivate(false);
+    m_controller->focusChanged(false);
+  }
+  m_focused = false;
 }
 
 void NavigatorVR::didAddEventListener(LocalDOMWindow* window,
                                       const AtomicString& eventType) {
   if (eventType == EventTypeNames::vrdisplayactivate) {
-    controller()->setListeningForActivate(true);
+    controller()->setListeningForActivate(m_focused);
     m_listeningForActivate = true;
   } else if (eventType == EventTypeNames::vrdisplayconnect) {
     // If the page is listening for connection events make sure we've created a