[inspector] introduced stepIntoAsync for chained callbacks

src/inspector/v8-debugger-agent-impl.h

Index: src/inspector/v8-debugger-agent-impl.h
diff --git a/src/inspector/v8-debugger-agent-impl.h b/src/inspector/v8-debugger-agent-impl.h
index 715b3c3fd78a718cc623ffb1527a3e9aabe437cd..697ecdabd4db9e9eb48b8d66e987d33a86c71793 100644
--- a/src/inspector/v8-debugger-agent-impl.h
+++ b/src/inspector/v8-debugger-agent-impl.h
@@ -87,6 +87,7 @@ class V8DebuggerAgentImpl : public protocol::Debugger::Backend {
   Response resume() override;
   Response stepOver() override;
   Response stepInto() override;
+  Response stepIntoAsync() override;
   Response stepOut() override;
   Response setPauseOnExceptions(const String16& pauseState) override;
   Response evaluateOnCallFrame(
@@ -141,6 +142,10 @@ class V8DebuggerAgentImpl : public protocol::Debugger::Backend {
 
   v8::Isolate* isolate() { return m_isolate; }
 
+  void asyncTaskCreated();
+  void asyncTaskStarted();
+  void asyncTaskFinished();
+
  private:
   void enableImpl();