Oilpan: prevent player from accessing its media element during finalization

Source/web/WebMediaPlayerClientImpl.cpp

Index: Source/web/WebMediaPlayerClientImpl.cpp
diff --git a/Source/web/WebMediaPlayerClientImpl.cpp b/Source/web/WebMediaPlayerClientImpl.cpp
index 3e58a63e22a147f0978a14fa5545b615d77dab4d..e31f3ccb9f153244274581c6eb9e5f007e842a13 100644
--- a/Source/web/WebMediaPlayerClientImpl.cpp
+++ b/Source/web/WebMediaPlayerClientImpl.cpp
@@ -73,7 +73,13 @@ WebMediaPlayerClientImpl::~WebMediaPlayerClientImpl()
     // Explicitly destroy the WebMediaPlayer to allow verification of tear down.
     m_webMediaPlayer.clear();
 
-    HTMLMediaElementEncryptedMedia::playerDestroyed(mediaElement());
+    if (m_client)
+        HTMLMediaElementEncryptedMedia::playerDestroyed(mediaElement());
+}
+
+void WebMediaPlayerClientImpl::detach()
+{
+    m_client = 0;
 }
 
 void WebMediaPlayerClientImpl::networkStateChanged()
@@ -143,7 +149,9 @@ void WebMediaPlayerClientImpl::keyNeeded(const WebString& contentType, const uns
 
 void WebMediaPlayerClientImpl::setWebLayer(blink::WebLayer* layer)
 {
-    m_client->mediaPlayerSetWebLayer(layer);
+    ASSERT(m_client || !layer);

[haraken, 2014/05/27 23:09:09]

Nit: I wonder why you need this ASSERT.

[sof, 2014/05/28 05:28:18]

To check that the embedder only tries to clear the layer when in a detached
state. Which the WebMediaPlayer does when it is torn down in the destructor
above.

Exposing a detached state on this client object isn't quite as
contained&restricted as I would have hoped for. Been going back&forth on this
overnight, and I think I prefer the first approach.

+    if (m_client)
+        m_client->mediaPlayerSetWebLayer(layer);
 }
 
 void WebMediaPlayerClientImpl::addTextTrack(WebInbandTextTrack* textTrack)