Move and rename TaskTimeTracker to public interface exposed to WebThread, use in WebPerf Agent.

third_party/WebKit/Source/core/inspector/InspectorWebPerfAgent.h

Index: third_party/WebKit/Source/core/inspector/InspectorWebPerfAgent.h
diff --git a/third_party/WebKit/Source/core/inspector/InspectorWebPerfAgent.h b/third_party/WebKit/Source/core/inspector/InspectorWebPerfAgent.h
index 09a7094e7b0163b262447cf08f6738939ad7d598..3aa0a3204bab1944e8c0d186c80a6be1e127111a 100644
--- a/third_party/WebKit/Source/core/inspector/InspectorWebPerfAgent.h
+++ b/third_party/WebKit/Source/core/inspector/InspectorWebPerfAgent.h
@@ -7,6 +7,7 @@
 
 #include "core/CoreExport.h"
 #include "platform/heap/Handle.h"
+#include "public/platform/WebThread.h"
 
 namespace blink {
 
@@ -15,16 +16,25 @@ class LocalFrame;
 class InspectedFrames;
 
 // Inspector Agent for Web Performance APIs
-class CORE_EXPORT InspectorWebPerfAgent final : public GarbageCollectedFinalized<InspectorWebPerfAgent> {
+class CORE_EXPORT InspectorWebPerfAgent final
+    : public GarbageCollectedFinalized<InspectorWebPerfAgent>
+    , private WebThread::TaskTimeObserver {
     WTF_MAKE_NONCOPYABLE(InspectorWebPerfAgent);
 public:
-    InspectorWebPerfAgent(InspectedFrames*);
+    static void enableInstrumentation(LocalFrame*);
+
+    explicit InspectorWebPerfAgent(InspectedFrames*);
     ~InspectorWebPerfAgent();
     DECLARE_VIRTUAL_TRACE();
 
     void willExecuteScript(ExecutionContext*);
     void didExecuteScript();
 
+    // WebThread::TaskTimeObserver implementation.
+    void willProcessTask() override;
+    void didProcessTask() override;
+    void reportTaskTime(double startTime, double endTime) override;
+
 private:
     Member<InspectedFrames> m_inspectedFrames;
 };