Notify WebMediaPlayer when its ancestor enters/exists fullscreen.

third_party/WebKit/Source/core/dom/Fullscreen.cpp

Index: third_party/WebKit/Source/core/dom/Fullscreen.cpp
diff --git a/third_party/WebKit/Source/core/dom/Fullscreen.cpp b/third_party/WebKit/Source/core/dom/Fullscreen.cpp
index f30793ebf893232c84067a756b252a75473c91a3..ebd0e7aa75fa7cd856fd155aa7777e682a242ef9 100644
--- a/third_party/WebKit/Source/core/dom/Fullscreen.cpp
+++ b/third_party/WebKit/Source/core/dom/Fullscreen.cpp
@@ -570,6 +570,9 @@ void Fullscreen::didEnterFullscreenForElement(Element* element) {
   if (document()->frame())
     document()->frame()->eventHandler().scheduleHoverStateUpdate();
 
+  for (FullscreenObserver* observer : m_observers)
+    observer->onEnteredFullscreen();
+
   m_eventQueueTimer.startOneShot(0, BLINK_FROM_HERE);
 }
 
@@ -608,6 +611,9 @@ void Fullscreen::didExitFullscreen() {
   from(*exitingDocument).m_eventQueueTimer.startOneShot(0, BLINK_FROM_HERE);
 
   m_forCrossProcessDescendant = false;
+
+  for (FullscreenObserver* observer : m_observers)
+    observer->onExitedFullscreen();
 }
 
 void Fullscreen::setFullScreenLayoutObject(LayoutFullScreen* layoutObject) {
@@ -725,6 +731,18 @@ void Fullscreen::pushFullscreenElementStack(Element& element,
   m_fullscreenElementStack.append(std::make_pair(&element, requestType));
 }
 
+void Fullscreen::registerObserver(FullscreenObserver* observer) {
+  if (m_observers.find(observer) != m_observers.end())
+    return;
+  m_observers.insert(observer);
+}
+
+void Fullscreen::removeObserver(FullscreenObserver* observer) {
+  if (m_observers.find(observer) == m_observers.end())
+    return;
+  m_observers.erase(observer);
+}
+
 DEFINE_TRACE(Fullscreen) {
   visitor->trace(m_currentFullScreenElement);
   visitor->trace(m_fullscreenElementStack);