Provide WebVR pose data only to the focused frame.

third_party/WebKit/Source/core/page/FocusChangedObserver.cpp

+// Copyright 2017 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 "core/page/FocusChangedObserver.h"
+
+#include "core/page/FocusController.h"
+#include "core/page/Page.h"
+
+namespace blink {
+
+bool FocusChangedObserver::isFrameFocused(LocalFrame* frame) {
+  if (!frame)
+    return false;
+  Page* page = frame->page();
+  if (!page)
+    return false;
+  const FocusController& controller = page->focusController();
+  return controller.isFocused() && (controller.focusedFrame() == frame);
+}
+
+void FocusChangedObserver::observe(Page* page) {
+  DCHECK(page);
+  page->focusController().registerFocusChangedObserver(this);
+}
+
+}  // namespace blink