Add step OverAwait to service protocol

runtime/observatory/lib/src/service/object.dart

Index: runtime/observatory/lib/src/service/object.dart
diff --git a/runtime/observatory/lib/src/service/object.dart b/runtime/observatory/lib/src/service/object.dart
index bd76e67d0caa9d24a4791ee05345935b0b0feb5e..78b67659cb2d5cb5c10f6de89740e658d846127e 100644
--- a/runtime/observatory/lib/src/service/object.dart
+++ b/runtime/observatory/lib/src/service/object.dart
@@ -1577,92 +1577,12 @@ class Isolate extends ServiceObjectOwner {
     return invokeRpc('resume', {'step': 'Over'});
   }
 
-  Future stepOut() {
-    return invokeRpc('resume', {'step': 'Out'});
+  Future stepOverAsyncSuspension() {
+    return invokeRpc('resume', {'step': 'OverAsyncSuspension'});
   }
 
-
-  static const int kFirstResume = 0;
-  static const int kSecondResume = 1;
-  /// result[kFirstResume] completes after the inital resume. The UI should
-  /// wait on this future because some other breakpoint may be hit before the
-  /// async continuation.
-  /// result[kSecondResume] completes after the second resume. Tests should
-  /// wait on this future to avoid confusing the pause event at the
-  /// state-machine switch with the pause event after the state-machine switch.
-  Future<List<Future>> asyncStepOver() async {
-    final Completer firstResume = new Completer();
-    final Completer secondResume = new Completer();
-    final List<Future> result = [firstResume.future, secondResume.future];
-    StreamSubscription subscription;
-
-    // Inner error handling function.
-    handleError(error) {
-      if (subscription != null) {
-        subscription.cancel();
-        subscription = null;
-      }
-      firstResume.completeError(error);
-      secondResume.completeError(error);
-    }
-
-    if ((pauseEvent == null) ||
-        (pauseEvent.kind != ServiceEvent.kPauseBreakpoint) ||
-        (pauseEvent.asyncContinuation == null)) {
-      handleError(new Exception("No async continuation available"));
-    } else {
-      Instance continuation = pauseEvent.asyncContinuation;
-      assert(continuation.isClosure);
-
-      // Add breakpoint at continuation.
-      Breakpoint continuationBpt;
-      try {
-        continuationBpt = await addBreakOnActivation(continuation);
-      } catch (e) {
-        handleError(e);
-        return result;
-      }
-
-      // Subscribe to the debugger event stream.
-      Stream stream;
-      try {
-        stream = await vm.getEventStream(VM.kDebugStream);
-      } catch (e) {
-        handleError(e);
-        return result;
-      }
-
-      Completer onResume = firstResume;
-      subscription = stream.listen((ServiceEvent event) async {
-        if ((event.kind == ServiceEvent.kPauseBreakpoint) &&
-            (event.breakpoint == continuationBpt)) {
-          // We are stopped before state-machine dispatch:
-          // 1) Remove the continuation breakpoint.
-          // 2) step over.
-          // reach user code.
-          await removeBreakpoint(continuationBpt);
-          onResume = secondResume;
-          stepOver().catchError(handleError);
-        } else if (event.kind == ServiceEvent.kResume) {
-          // We've resumed.
-          if (onResume == secondResume) {
-            // This is our second resume, cancel our subscription to the debug
-            // stream.
-            subscription.cancel();
-            subscription = null;
-          }
-          // Complete onResume and clear it.
-          if (onResume != null) {
-            onResume.complete(this);
-            onResume = null;
-          }
-        }
-      });
-
-      // Call resume, which will eventually cause us to hit continuationBpt.
-      resume().catchError(handleError);
-    }
-    return result;
+  Future stepOut() {
+    return invokeRpc('resume', {'step': 'Out'});
   }
 
   Future setName(String newName) {
@@ -1914,8 +1834,7 @@ class ServiceEvent extends ServiceObject {
   @observable Frame topFrame;
   @observable String extensionRPC;
   @observable Instance exception;
-  @observable Instance asyncContinuation;
-  @observable bool atAsyncJump;
+  @observable bool atAsyncSuspension;
   @observable ServiceObject inspectee;
   @observable ByteData data;
   @observable int count;
@@ -1964,12 +1883,7 @@ class ServiceEvent extends ServiceObject {
     if (map['exception'] != null) {
       exception = map['exception'];
     }
-    if (map['_asyncContinuation'] != null) {
-      asyncContinuation = map['_asyncContinuation'];
-      atAsyncJump = map['_atAsyncJump'];
-    } else {
-      atAsyncJump = false;
-    }
+    atAsyncSuspension = map['atAsyncSuspension'] != null;
     if (map['inspectee'] != null) {
       inspectee = map['inspectee'];
     }
@@ -2040,6 +1954,10 @@ class Breakpoint extends ServiceObject {
   // The breakpoint has been assigned to a final source location.
   @observable bool resolved;
 
+  // The breakpoint was synthetically created as part of an
+  // 'OverAsyncContinuation' resume request.
+  @observable bool isSyntheticAsyncContinuation;
+
   void _update(ObservableMap map, bool mapIsRef) {
     _loaded = true;
     _upgradeCollection(map, owner);
@@ -2066,6 +1984,8 @@ class Breakpoint extends ServiceObject {
       newScript._addBreakpoint(this);
     }
 
+    isSyntheticAsyncContinuation = map['isSyntheticAsyncContinuation'] != null;
+
     assert(resolved || location is UnresolvedSourceLocation);
   }
 
@@ -2081,7 +2001,11 @@ class Breakpoint extends ServiceObject {
 
   String toString() {
     if (number != null) {
-      return 'Breakpoint ${number} at ${location})';
+      if (isSyntheticAsyncContinuation) {
+        return 'Synthetic Async Continuation Breakpoint ${number}';
+      } else {
+        return 'Breakpoint ${number} at ${location}';
+      }
     } else {
       return 'Uninitialized breakpoint';
     }