Bug 1499828 Part 1 - Add API for getting the current recording position, r=mccr8.

--HG--
extra : rebase_source : c04a4504f9e46e4a727c724834f97c1d7dce2417

toolkit/recordreplay/ipc/JSControl.cpp

@@ -432,6 +432,21 @@ Middleman_HadRepaintFailure(JSContext* aCx, unsigned aArgc, Value* aVp)
   return true;
 }
 
+static bool
+Middleman_RecordingPosition(JSContext* aCx, unsigned aArgc, Value* aVp)
+{
+  CallArgs args = CallArgsFromVp(aArgc, aVp);
+
+  Maybe<double> recordingPosition = parent::GetRecordingPosition();
+
+  if (recordingPosition.isSome()) {
+    args.rval().setNumber(recordingPosition.ref());
+  } else {
+    args.rval().setUndefined();
+  }
+  return true;
+}
+
 ///////////////////////////////////////////////////////////////////////////////
 // Devtools Sandbox
 ///////////////////////////////////////////////////////////////////////////////
@@ -912,6 +927,7 @@ static const JSFunctionSpec gMiddlemanMethods[] = {
   JS_FN("maybeSwitchToReplayingChild", Middleman_MaybeSwitchToReplayingChild, 0, 0),
   JS_FN("hadRepaint", Middleman_HadRepaint, 2, 0),
   JS_FN("hadRepaintFailure", Middleman_HadRepaintFailure, 0, 0),
+  JS_FN("recordingPosition", Middleman_RecordingPosition, 0, 0),
   JS_FS_END
 };
 

toolkit/recordreplay/ipc/ParentIPC.cpp

@@ -857,6 +857,19 @@ MaybeSwitchToReplayingChild()
   }
 }
 
+Maybe<double>
+GetRecordingPosition()
+{
+  if (gActiveChild->IsRecording()) {
+    return Nothing();
+  }
+
+  // Get the fraction of the recording that the active child has reached so far.
+  double fraction = (gActiveChild->MostRecentCheckpoint() - CheckpointId::First)
+                  / (double) (gCheckpointTimes.length() - CheckpointId::First);
+  return Some(fraction);
+}
+
 ///////////////////////////////////////////////////////////////////////////////
 // Initialization
 ///////////////////////////////////////////////////////////////////////////////

toolkit/recordreplay/ipc/ParentInternal.h

@@ -76,6 +76,10 @@ void SetBreakpoint(size_t aId, const js::BreakpointPosition& aPosition);
 // children cannot process such requests).
 void MaybeSwitchToReplayingChild();
 
+// If the active child is replaying, get its fractional (range [0,1]) position
+// in the recording. If the active child is recording, return Nothing.
+Maybe<double> GetRecordingPosition();
+
 ///////////////////////////////////////////////////////////////////////////////
 // Graphics
 ///////////////////////////////////////////////////////////////////////////////