DevTools: simplify the async instrumentation harness.

third_party/WebKit/Source/core/dom/MutationObserver.cpp

Index: third_party/WebKit/Source/core/dom/MutationObserver.cpp
diff --git a/third_party/WebKit/Source/core/dom/MutationObserver.cpp b/third_party/WebKit/Source/core/dom/MutationObserver.cpp
index 7b233e00d06c7b915d2d787c963c2587ce647217..66d217ca0ed39e821879d52b002b2682b51e44ce 100644
--- a/third_party/WebKit/Source/core/dom/MutationObserver.cpp
+++ b/third_party/WebKit/Source/core/dom/MutationObserver.cpp
@@ -69,8 +69,7 @@ MutationObserver::~MutationObserver()
 #if !ENABLE(OILPAN)
     ASSERT(m_registrations.isEmpty());
 #endif
-    if (!m_records.isEmpty())
-        InspectorInstrumentation::didClearAllMutationRecords(m_callback->getExecutionContext(), this);
+    cancelInspectorAsyncTasks();
 }
 
 void MutationObserver::observe(Node* node, const MutationObserverInit& observerInit, ExceptionState& exceptionState)
@@ -133,15 +132,15 @@ void MutationObserver::observe(Node* node, const MutationObserverInit& observerI
 MutationRecordVector MutationObserver::takeRecords()
 {
     MutationRecordVector records;
+    cancelInspectorAsyncTasks();
     records.swap(m_records);
-    InspectorInstrumentation::didClearAllMutationRecords(m_callback->getExecutionContext(), this);
     return records;
 }
 
 void MutationObserver::disconnect()
 {
+    cancelInspectorAsyncTasks();
     m_records.clear();
-    InspectorInstrumentation::didClearAllMutationRecords(m_callback->getExecutionContext(), this);
     MutationObserverRegistrationSet registrations(m_registrations);
     for (auto& registration : registrations) {
         // The registration may be already unregistered while iteration.
@@ -189,7 +188,7 @@ void MutationObserver::enqueueMutationRecord(RawPtr<MutationRecord> mutation)
     ASSERT(isMainThread());
     m_records.append(mutation);
     activateObserver(this);
-    InspectorInstrumentation::didEnqueueMutationRecord(m_callback->getExecutionContext(), this);
+    InspectorInstrumentation::asyncTaskScheduled(m_callback->getExecutionContext(), mutation->type(), mutation);
 }
 
 void MutationObserver::setHasTransientRegistration()
@@ -211,6 +210,12 @@ bool MutationObserver::shouldBeSuspended() const
     return m_callback->getExecutionContext() && m_callback->getExecutionContext()->activeDOMObjectsAreSuspended();
 }
 
+void MutationObserver::cancelInspectorAsyncTasks()
+{
+    for (auto& record : m_records)
+        InspectorInstrumentation::asyncTaskCanceled(m_callback->getExecutionContext(), record);
+}
+
 void MutationObserver::deliver()
 {
     ASSERT(!shouldBeSuspended());
@@ -231,9 +236,9 @@ void MutationObserver::deliver()
     MutationRecordVector records;
     records.swap(m_records);
 
-    InspectorInstrumentation::willDeliverMutationRecords(m_callback->getExecutionContext(), this);
+    // Report the first (earliest) stack as the async cause.
+    InspectorInstrumentation::AsyncTask asyncTask(m_callback->getExecutionContext(), records.first());
     m_callback->call(records, this);
-    InspectorInstrumentation::didDeliverMutationRecords(m_callback->getExecutionContext());
 }
 
 void MutationObserver::resumeSuspendedObservers()