Stop firing orientationchange events at pages that are not visible

Source/modules/screen_orientation/ScreenOrientation.cpp

Index: Source/modules/screen_orientation/ScreenOrientation.cpp
diff --git a/Source/modules/screen_orientation/ScreenOrientation.cpp b/Source/modules/screen_orientation/ScreenOrientation.cpp
index d428f1a2fbc710cdc6589fc0ba4de4f36710c11b..bb0fb9d1b68f083f0398a671349a0b46c474e141 100644
--- a/Source/modules/screen_orientation/ScreenOrientation.cpp
+++ b/Source/modules/screen_orientation/ScreenOrientation.cpp
@@ -5,6 +5,7 @@
 #include "config.h"
 #include "modules/screen_orientation/ScreenOrientation.h"
 
+#include "core/dom/FullscreenElementStack.h"
 #include "core/frame/DOMWindow.h"
 #include "core/frame/LocalFrame.h"
 #include "core/frame/Screen.h"
@@ -101,6 +102,39 @@ void ScreenOrientation::orientationLockTimerFired(Timer<ScreenOrientation>*)
         blink::Platform::current()->lockOrientation(m_prospectiveLock);
 }
 
+void ScreenOrientation::startListeningForFullscreenExit()
+{
+    Document* document = this->document();
+    ASSERT(document);
+    FullscreenElementStack* fullscreen = FullscreenElementStack::fromIfExists(*document);
+    ASSERT(fullscreen);
+    fullscreen->addObserver(this);
+}
+
+void ScreenOrientation::stopListeningForFullscreenExit()
+{
+    Document* document = this->document();
+    if (!document)
+        return;
+    FullscreenElementStack* fullscreen = FullscreenElementStack::fromIfExists(*document);
+    if (!fullscreen)
+        return;
+    fullscreen->removeObserver(this);
+}
+
+// We need to set the screen orientation lock back to the default when
+// the document fully exists fullscreen.
+void ScreenOrientation::didFullyExitFullscreen()
+{
+    stopListeningForFullscreenExit();
+
+    m_prospectiveLock = blink::WebScreenOrientationLockDefault;
+    if (m_orientationLockTimer.isActive())
+        m_orientationLockTimer.stop();
+
+    blink::Platform::current()->unlockOrientation();
+}
+
 const char* ScreenOrientation::supplementName()
 {
     return "ScreenOrientation";
@@ -126,6 +160,7 @@ ScreenOrientation& ScreenOrientation::from(Screen& screen)
 
 ScreenOrientation::~ScreenOrientation()
 {
+    stopListeningForFullscreenExit();

[sof, 2014/05/08 21:41:17]

With Oilpan, this is a somewhat problematic cleanup action, as it runs the risk
of touching a now-dead DOMWindow. But can m_associatedDOMWindow (which
document() consults) be anything other than 0? If it can't, then this call has
no effect. If it can be non-zero, then I think you need to override
willDestroyGlobalObjectInFrame() instead and remove the fullscreen observer from
there.

 }
 
 const AtomicString& ScreenOrientation::orientation(Screen& screen)
@@ -139,15 +174,31 @@ const AtomicString& ScreenOrientation::orientation(Screen& screen)
     return orientationTypeToString(controller.orientation());
 }
 
+bool ScreenOrientation::isOrientationLockingAllowed(Document& document) const
+{
+    // We only allow locking the orientation while in fullscreen, for consistency with other browsers.
+    return FullscreenElementStack::isFullScreen(document);
+}
+
 bool ScreenOrientation::lockOrientation(Screen& screen, const AtomicString& lockString)
 {
-    ScreenOrientation::from(screen).lockOrientationAsync(stringToOrientationLock(lockString));
+    ScreenOrientation& screenOrientation = ScreenOrientation::from(screen);
+    Document* document = screenOrientation.document();
+    if (!document)
+        return false;
+    if (!screenOrientation.isOrientationLockingAllowed(*document))
+        return false;
+
+    screenOrientation.lockOrientationAsync(stringToOrientationLock(lockString));
+    screenOrientation.startListeningForFullscreenExit();
     return true;
 }
 
 void ScreenOrientation::unlockOrientation(Screen& screen)
 {
-    ScreenOrientation::from(screen).lockOrientationAsync(blink::WebScreenOrientationLockDefault);
+    ScreenOrientation& screenOrientation = ScreenOrientation::from(screen);
+    screenOrientation.stopListeningForFullscreenExit();
+    screenOrientation.lockOrientationAsync(blink::WebScreenOrientationLockDefault);
 }
 
 } // namespace WebCore