Introduce AnimationWorkletProxyClient and necessary plumbing to get it in worklet messaging proxy.

third_party/WebKit/Source/core/dom/CompositorProxyClient.h

Index: third_party/WebKit/Source/core/dom/CompositorProxyClient.h
diff --git a/third_party/WebKit/Source/core/dom/CompositorProxyClient.h b/third_party/WebKit/Source/core/dom/CompositorProxyClient.h
index 95c056a362ddd3d069cb20fcbea6f8aac30c1e85..58095f7cb28baaed0dab4f22fb02cc28c128daf2 100644
--- a/third_party/WebKit/Source/core/dom/CompositorProxyClient.h
+++ b/third_party/WebKit/Source/core/dom/CompositorProxyClient.h
@@ -6,29 +6,18 @@
 #define CompositorProxyClient_h
 
 #include "core/CoreExport.h"
-#include "core/workers/WorkerClients.h"
-#include "wtf/Noncopyable.h"
-
-#include <v8.h>
+#include "platform/heap/Handle.h"
 
 namespace blink {
 
 class CompositorProxy;
-class WorkerClients;
-class WorkerGlobalScope;
-
-class CORE_EXPORT CompositorProxyClient : public Supplement<WorkerClients> {
-  WTF_MAKE_NONCOPYABLE(CompositorProxyClient);
 
+class CORE_EXPORT CompositorProxyClient : public GarbageCollectedMixin {

[dcheng, 2016/11/28 21:17:31]

Nit: it might be slightly simpler just to make this a GarbageCollectedFinalized:
it feels weird for derived classes to have to call
CompositorProxyClient::trace() when nothing is ever traced.

Alternatively... would it make sense to just have createWorkerClient() and
createWorkletClient() here and just have it return an
AnimationProxyWorkletClient / CompositorProxyWorkerClient here? Is there code
that will need to work with either one in a transparent manner?

[majidvp, 2017/01/20 15:48:57]

Good idea. Done!
I don't think I can construct the clients here. To construct one, we need
to have a reference to CompositorMutatorImpl which is available in WebViewImpl
which is why the clients are constructed there.

  public:
-  CompositorProxyClient() {}
+  enum Type { kWorkerClient, kWorkletClient };

[dcheng, 2016/11/28 21:17:31]

Nit: can we document the distinction between 'worker' and 'worklet' somewhere? I
don't actually know what the difference is...

[majidvp, 2017/01/20 15:48:57]

I don't know if there is a design doc for worklets but ikilpatrick@ maybe able
to
point one out. Here is the spec which talks about the difference between worker
and a worklet https://drafts.css-houdini.org/worklets/.

 
-  static CompositorProxyClient* from(WorkerClients*);
-  static const char* supplementName();
+  DEFINE_INLINE_VIRTUAL_TRACE() {}
 
-  virtual void dispose() = 0;
-  virtual void setGlobalScope(WorkerGlobalScope*) = 0;
-  virtual void requestAnimationFrame() = 0;
   virtual void registerCompositorProxy(CompositorProxy*) = 0;
   // It is not guaranteed to receive an unregister call for every registered
   // proxy. In fact we only receive one when a proxy is explicitly
@@ -37,9 +26,6 @@ class CORE_EXPORT CompositorProxyClient : public Supplement<WorkerClients> {
   virtual void unregisterCompositorProxy(CompositorProxy*) = 0;
 };
 
-CORE_EXPORT void provideCompositorProxyClientTo(WorkerClients*,
-                                                CompositorProxyClient*);
-
 }  // namespace blink
 
 #endif  // CompositorProxyClient_h