[oilpan]: Don't assert the context is destroyed _after_ the NewWebSocketChannelImpl in oilpan.

This should fix a couple of the crashes we are seeing in the debug oilpan builds for websockets.

R=ager@chromium.org, erik.corry@gmail.com, haraken@chromium.org, oilpan-reviews@chromium.org, tkent@chromium.org, tyoshino@chromium.org, vegorov@chromium.org, yhirano@chromium.org, zerny@chromium.org
BUG=

Review URL: https://codereview.chromium.org/405453002

git-svn-id: svn://svn.chromium.org/blink/trunk@178379 bbb929c8-8fbe-4397-9dbb-9b2b20218538

third_party/WebKit/Source/modules/websockets/NewWebSocketChannelImpl.h

@@ -149,8 +149,24 @@ private:
     void didFailLoadingBlob(FileError::ErrorCode);
 
     // LifecycleObserver functions.
-    // This object must be destroyed before the context.
-    virtual void contextDestroyed() OVERRIDE { ASSERT_NOT_REACHED(); }
+    virtual void contextDestroyed() OVERRIDE
+    {
+#if ENABLE(OILPAN)
+        // In oilpan we cannot assume this channel's finalizer has been called
+        // before the document it is observing is dead and finalized since there
+        // is no eager finalization. Instead the finalization happens at the
+        // next GC which could be long enough after the Peer::destroy call for
+        // the context (ie. Document) to be dead too. If the context's finalizer
+        // is run first this method gets called. Instead we assert the channel
+        // has been disconnected which happens in Peer::destroy.
+        ASSERT(!m_handle);
+        ASSERT(!m_client);
+        ASSERT(!m_identifier);
+#else
+        // This object must be destroyed before the context.
+        ASSERT_NOT_REACHED();
+#endif
+    }
 
     // m_handle is a handle of the connection.
     // m_handle == 0 means this channel is closed.