rAF: Introduce FrameRequestCallbackCollection for managing rAF callbacks.

Source/core/inspector/InspectorTraceEvents.cpp

Index: Source/core/inspector/InspectorTraceEvents.cpp
diff --git a/Source/core/inspector/InspectorTraceEvents.cpp b/Source/core/inspector/InspectorTraceEvents.cpp
index 261f48465cc5982b5320b3c2ca0a34e5ea27fba2..6337aab7b4725b7b91686dee0644f8c7802001c5 100644
--- a/Source/core/inspector/InspectorTraceEvents.cpp
+++ b/Source/core/inspector/InspectorTraceEvents.cpp
@@ -426,11 +426,14 @@ PassRefPtr<TraceEvent::ConvertableToTraceFormat> InspectorTimerFireEvent::data(E
     return genericTimerData(context, timerId);
 }
 
-PassRefPtr<TraceEvent::ConvertableToTraceFormat> InspectorAnimationFrameEvent::data(Document* document, int callbackId)
+PassRefPtr<TraceEvent::ConvertableToTraceFormat> InspectorAnimationFrameEvent::data(ExecutionContext* context, int callbackId)

[dgozman, 2015/03/31 10:10:05]

Maybe this whole event makes sense only for document? +caseq@ to answer this.

[caseq, 2015/03/31 10:27:42]

From what I understand, we can no longer assume the execution context is a
Document becuase the code is being generalized to handle compositor workers. If
so, the trace events should be fine(*), but I'm worried for
InspectorInstrumentation calls -- these may only be invoked by the main thread.

(*) we may still want some way of identifying the context, so we can tell apart
workers for different pages if they share the process, but I think this can be
deferred to a later stage, considering it would require some front-end support.

[sadrul, 2015/03/31 12:39:41]

Considering for the Document, we simply list the pointer to the frame, would it
make sense to do something similar for the worker like this:

  if (context->isDocument()) {
    value->SetString("frame", toHexString(toDocument(context)->frame()));
  } else if (context->isGlobalWorkerScope()) {
    value->SetString("worker", toHexString(toWorkerGlobalScope(context)));
  }

?

[sadrul, 2015/03/31 16:40:27]

Done.

 {
     RefPtr<TracedValue> value = TracedValue::create();
     value->setInteger("id", callbackId);
-    value->setString("frame", toHexString(document->frame()));
+    if (context->isDocument()) {
+        Document* document = toDocument(context);
+        value->setString("frame", toHexString(document->frame()));
+    }
     setCallStack(value.get());
     return value.release();
 }