Bug 1550092 part 3. Stop using [array] in stopFrameTimeRecording. r=farre

Differential Revision: https://phabricator.services.mozilla.com/D30443

--HG--
extra : moz-landing-system : lando

dom/base/nsDOMWindowUtils.cpp

@@ -2231,28 +2231,14 @@ nsDOMWindowUtils::StartFrameTimeRecording(uint32_t* startIndex) {
 
 NS_IMETHODIMP
 nsDOMWindowUtils::StopFrameTimeRecording(uint32_t startIndex,
-                                         uint32_t* frameCount,
-                                         float** frameIntervals) {
-  NS_ENSURE_ARG_POINTER(frameCount);
-  NS_ENSURE_ARG_POINTER(frameIntervals);
-
+                                         nsTArray<float>& frameIntervals) {
   nsCOMPtr<nsIWidget> widget = GetWidget();
   if (!widget) return NS_ERROR_FAILURE;
 
   LayerManager* mgr = widget->GetLayerManager();
   if (!mgr) return NS_ERROR_FAILURE;
 
-  nsTArray<float> tmpFrameIntervals;
-  mgr->StopFrameTimeRecording(startIndex, tmpFrameIntervals);
-  *frameCount = tmpFrameIntervals.Length();
-
-  *frameIntervals = (float*)moz_xmalloc(*frameCount * sizeof(float));
-
-  /* copy over the frame intervals and paint times into the arrays we just
-   * allocated */
-  for (uint32_t i = 0; i < *frameCount; i++) {
-    (*frameIntervals)[i] = tmpFrameIntervals[i];
-  }
+  mgr->StopFrameTimeRecording(startIndex, frameIntervals);
 
   return NS_OK;
 }

dom/interfaces/base/nsIDOMWindowUtils.idl

@@ -1349,13 +1349,10 @@ interface nsIDOMWindowUtils : nsISupports {
   void startFrameTimeRecording([retval] out unsigned long startIndex);
 
   /**
-   * Returns number of recorded frames since startIndex was issued,
-   *   and allocates+populates 2 arraye with the recorded data.
-   * - Allocation is infallible. Should be released even if size is 0.
+   * Returns array of frame intervals since the time when the given startIndex
+   * was handed out from startFrameTimeRecording.
    */
-  void stopFrameTimeRecording(in unsigned long startIndex,
-                             [optional] out unsigned long frameCount,
-                             [retval, array, size_is(frameCount)] out float frameIntervals);
+  Array<float> stopFrameTimeRecording(in unsigned long startIndex);
 
   /**
    * The DPI of the display

testing/talos/talos/tests/tart/addon/content/tart.js

@@ -247,9 +247,8 @@ Tart.prototype = {
         Profiler.mark("End: " + (isReportResult ? name : "[warmup]"), true);
       }
       if (self.USE_RECORDING_API) {
-        var paints = {};
         return window.windowUtils
-                     .stopFrameTimeRecording(recordingHandle, paints);
+                     .stopFrameTimeRecording(recordingHandle);
       }
 
       _abortRecording = true;