compositor-worker: Share a thread and an isolate for compositor workers.

Source/core/workers/WorkerThread.h

Index: Source/core/workers/WorkerThread.h
diff --git a/Source/core/workers/WorkerThread.h b/Source/core/workers/WorkerThread.h
index 2405c86493da3a2d74d818d58207bc8e2333576c..cad181ebbc1612972d2439181231532adf40087a 100644
--- a/Source/core/workers/WorkerThread.h
+++ b/Source/core/workers/WorkerThread.h
@@ -31,6 +31,7 @@
 #include "core/dom/ExecutionContextTask.h"
 #include "core/frame/csp/ContentSecurityPolicy.h"
 #include "core/workers/WorkerGlobalScope.h"
+#include "core/workers/WorkerIsolateWrapper.h"
 #include "core/workers/WorkerLoaderProxy.h"
 #include "platform/WebThreadSupportingGC.h"
 #include "platform/weborigin/SecurityOrigin.h"
@@ -69,11 +70,10 @@ public:
     // some implementations can use an existing thread that is already being
     // used by other workers (e.g.  compositor workers).
     virtual WebThreadSupportingGC& backingThread() = 0;
-
     virtual void didStartRunLoop();
     virtual void didStopRunLoop();
 
-    v8::Isolate* isolate() const { return m_isolate; }
+    v8::Isolate* isolate();
 
     // Can be used to wait for this worker thread to shut down.
     // (This is signalled on the main thread, so it's assumed to be waited on the worker context thread)
@@ -122,11 +122,12 @@ protected:
 
     virtual void postInitialize() { }
 
-    virtual v8::Isolate* initializeIsolate();
-    virtual void willDestroyIsolate();
-    virtual void destroyIsolate();
+    virtual PassOwnPtr<WorkerIsolateWrapper> createIsolateWrapper() = 0;

[kinuko, 2015/06/01 13:15:41]

Please comment that this needs to be called on the worker thread. (Also might be
nice to to put this after shutdownBackingThread so that the virtual methods that
are to be called on the worker thread are placed together)

[sadrul, 2015/06/01 14:21:16]

Done.

     virtual void terminateV8Execution();
 
+    virtual void initializeBackingThread();
+    virtual void shutdownBackingThread();

[kinuko, 2015/06/01 13:15:41]

Please comment that these need to be called on the worker thread.

[sadrul, 2015/06/01 14:21:16]

Done.

+
     // This is protected virtual for testing.
     virtual bool doIdleGc(double deadlineSeconds);
 
@@ -155,13 +156,11 @@ private:
     RefPtrWillBePersistent<WorkerInspectorController> m_workerInspectorController;
     Mutex m_workerInspectorControllerMutex;
 
-    // This lock protects |m_workerGlobalScope|, |m_terminated|, |m_isolate| and |m_microtaskRunner|.
+    // This lock protects |m_workerGlobalScope|, |m_terminated|, and |m_isolateWrapper|.
     Mutex m_threadStateMutex;
 
     RefPtrWillBePersistent<WorkerGlobalScope> m_workerGlobalScope;
-
-    v8::Isolate* m_isolate;
-    OwnPtr<V8IsolateInterruptor> m_interruptor;
+    OwnPtr<WorkerIsolateWrapper> m_isolateWrapper;
 
     // Used to signal thread shutdown.
     OwnPtr<WebWaitableEvent> m_shutdownEvent;