Bug 1590582 - Have AsyncPanZoomController::ConvertToGecko return a Maybe rather than using a bool + outparam. r=tnikkel

Depends on D50362

Differential Revision: https://phabricator.services.mozilla.com/D50363

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

gfx/layers/apz/src/AsyncPanZoomController.cpp

@@ -1859,21 +1859,17 @@ nsEventStatus AsyncPanZoomController::HandleEndOfPan() {
   return nsEventStatus_eConsumeNoDefault;
 }
 
-bool AsyncPanZoomController::ConvertToGecko(const ScreenIntPoint& aPoint,
-                                            LayoutDevicePoint* aOut) {
+Maybe<LayoutDevicePoint> AsyncPanZoomController::ConvertToGecko(
+    const ScreenIntPoint& aPoint) {
   if (APZCTreeManager* treeManagerLocal = GetApzcTreeManager()) {
-    Maybe<ScreenIntPoint> layoutPoint =
-        treeManagerLocal->ConvertToGecko(aPoint, this);
-    if (!layoutPoint) {
-      return false;
+    if (Maybe<ScreenIntPoint> layoutPoint =
+            treeManagerLocal->ConvertToGecko(aPoint, this)) {
+      return Some(LayoutDevicePoint(ViewAs<LayoutDevicePixel>(
+          *layoutPoint,
+          PixelCastJustification::LayoutDeviceIsScreenForUntransformedEvent)));
     }
-
-    *aOut = LayoutDevicePoint(ViewAs<LayoutDevicePixel>(
-        *layoutPoint,
-        PixelCastJustification::LayoutDeviceIsScreenForUntransformedEvent));
-    return true;
   }
-  return false;
+  return Nothing();
 }
 
 CSSCoord AsyncPanZoomController::ConvertScrollbarPoint(
@@ -2712,8 +2708,8 @@ nsEventStatus AsyncPanZoomController::OnLongPress(
   APZC_LOG("%p got a long-press in state %d\n", this, mState);
   RefPtr<GeckoContentController> controller = GetGeckoContentController();
   if (controller) {
-    LayoutDevicePoint geckoScreenPoint;
-    if (ConvertToGecko(aEvent.mPoint, &geckoScreenPoint)) {
+    if (Maybe<LayoutDevicePoint> geckoScreenPoint =
+            ConvertToGecko(aEvent.mPoint)) {
       TouchBlockState* touch = GetCurrentTouchBlock();
       if (!touch) {
         APZC_LOG(
@@ -2727,7 +2723,7 @@ nsEventStatus AsyncPanZoomController::OnLongPress(
         return nsEventStatus_eIgnore;
       }
       uint64_t blockId = GetInputQueue()->InjectNewTouchBlock(this);
-      controller->HandleTap(TapType::eLongTap, geckoScreenPoint,
+      controller->HandleTap(TapType::eLongTap, *geckoScreenPoint,
                             aEvent.modifiers, GetGuid(), blockId);
       return nsEventStatus_eConsumeNoDefault;
     }
@@ -2747,8 +2743,7 @@ nsEventStatus AsyncPanZoomController::GenerateSingleTap(
     mozilla::Modifiers aModifiers) {
   RefPtr<GeckoContentController> controller = GetGeckoContentController();
   if (controller) {
-    LayoutDevicePoint geckoScreenPoint;
-    if (ConvertToGecko(aPoint, &geckoScreenPoint)) {
+    if (Maybe<LayoutDevicePoint> geckoScreenPoint = ConvertToGecko(aPoint)) {
       TouchBlockState* touch = GetCurrentTouchBlock();
       // |touch| may be null in the case where this function is
       // invoked by GestureEventListener on a timeout. In that case we already
@@ -2775,7 +2770,7 @@ nsEventStatus AsyncPanZoomController::GenerateSingleTap(
           NewRunnableMethod<TapType, LayoutDevicePoint, mozilla::Modifiers,
                             ScrollableLayerGuid, uint64_t>(
               "layers::GeckoContentController::HandleTap", controller,
-              &GeckoContentController::HandleTap, aType, geckoScreenPoint,
+              &GeckoContentController::HandleTap, aType, *geckoScreenPoint,
               aModifiers, GetGuid(), touch ? touch->GetBlockId() : 0);
 
       controller->PostDelayedTask(runnable.forget(), 0);
@@ -2823,9 +2818,9 @@ nsEventStatus AsyncPanZoomController::OnDoubleTap(
     MOZ_ASSERT(GetCurrentTouchBlock());
     if (mZoomConstraints.mAllowDoubleTapZoom &&
         GetCurrentTouchBlock()->TouchActionAllowsDoubleTapZoom()) {
-      LayoutDevicePoint geckoScreenPoint;
-      if (ConvertToGecko(aEvent.mPoint, &geckoScreenPoint)) {
-        controller->HandleTap(TapType::eDoubleTap, geckoScreenPoint,
+      if (Maybe<LayoutDevicePoint> geckoScreenPoint =
+              ConvertToGecko(aEvent.mPoint)) {
+        controller->HandleTap(TapType::eDoubleTap, *geckoScreenPoint,
                               aEvent.modifiers, GetGuid(),
                               GetCurrentTouchBlock()->GetBlockId());
       }

gfx/layers/apz/src/AsyncPanZoomController.h

@@ -885,7 +885,7 @@ class AsyncPanZoomController {
    * NOTE: This must be converted to LayoutDevicePoint relative to the child
    * document before sending over IPC to a child process.
    */
-  bool ConvertToGecko(const ScreenIntPoint& aPoint, LayoutDevicePoint* aOut);
+  Maybe<LayoutDevicePoint> ConvertToGecko(const ScreenIntPoint& aPoint);
 
   enum AxisLockMode {
     FREE,     /* No locking at all */