Bug 1539521 - replace MaybeTransform IPDL union with native Maybe syntax; r=kats

Differential Revision: https://phabricator.services.mozilla.com/D25079

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

dom/base/nsDOMWindowUtils.cpp

@@ -3500,14 +3500,14 @@ nsDOMWindowUtils::GetOMTCTransform(Element* aElement,
     return NS_OK;
   }
 
-  MaybeTransform transform;
+  Maybe<Matrix4x4> transform;
   forwarder->GetShadowManager()->SendGetTransform(
       layer->AsShadowableLayer()->GetShadow(), &transform);
-  if (transform.type() != MaybeTransform::TMatrix4x4) {
+  if (transform.isNothing()) {
     return NS_OK;
   }
 
-  Matrix4x4 matrix = transform.get_Matrix4x4();
+  Matrix4x4 matrix = transform.value();
   RefPtr<nsROCSSPrimitiveValue> cssValue =
       nsComputedDOMStyle::MatrixToCSSValue(matrix);
   if (!cssValue) {

gfx/layers/ipc/LayerTransactionParent.cpp

@@ -699,7 +699,7 @@ mozilla::ipc::IPCResult LayerTransactionParent::RecvGetAnimationValue(
 }
 
 mozilla::ipc::IPCResult LayerTransactionParent::RecvGetTransform(
-    const LayerHandle& aLayerHandle, MaybeTransform* aTransform) {
+    const LayerHandle& aLayerHandle, Maybe<Matrix4x4>* aTransform) {
   if (mDestroyed || !mLayerManager || mLayerManager->IsDestroyed()) {
     return IPC_FAIL_NO_REASON(this);
   }
@@ -753,7 +753,7 @@ mozilla::ipc::IPCResult LayerTransactionParent::RecvGetTransform(
     transform *= layer->GetParent()->AsHostLayer()->GetShadowBaseTransform();
   }
 
-  *aTransform = transform;
+  *aTransform = Some(transform);
 
   return IPC_OK();
 }
@@ -807,7 +807,7 @@ mozilla::ipc::IPCResult LayerTransactionParent::RecvSetConfirmedTargetAPZC(
       NS_ERROR(
           "Unexpected render root in RecvSetConfirmedTargetAPZC; dropping "
           "message...");
-      return IPC_FAIL(this, "Bad render root"); 
+      return IPC_FAIL(this, "Bad render root");
     }
     if (aTargets[i].mScrollableLayerGuid.mLayersId != GetId()) {
       NS_ERROR(

gfx/layers/ipc/LayerTransactionParent.h

@@ -120,7 +120,7 @@ class LayerTransactionParent final : public PLayerTransactionParent,
   mozilla::ipc::IPCResult RecvGetAnimationValue(
       const uint64_t& aCompositorAnimationsId, OMTAValue* aValue);
   mozilla::ipc::IPCResult RecvGetTransform(const LayerHandle& aHandle,
-                                           MaybeTransform* aTransform);
+                                           Maybe<Matrix4x4>* aTransform);
   mozilla::ipc::IPCResult RecvSetAsyncScrollOffset(
       const ScrollableLayerGuid::ViewID& aId, const float& aX, const float& aY);
   mozilla::ipc::IPCResult RecvSetAsyncZoom(

gfx/layers/ipc/LayersMessages.ipdlh

@@ -563,11 +563,6 @@ struct TransactionInfo
   CompositionPayload[] payload;
 };
 
-union MaybeTransform {
-  Matrix4x4;
-  void_t;
-};
-
 union OMTAValue {
   null_t;
   nscolor;

gfx/layers/ipc/PLayerTransaction.ipdl

@@ -81,7 +81,7 @@ parent:
 
   // Returns the value of the transform applied to the layer by animation and
   // APZC.
-  sync GetTransform(LayerHandle layer) returns (MaybeTransform transform);
+  sync GetTransform(LayerHandle layer) returns (Matrix4x4? transform);
 
   // The next time the layer tree is composited, add this async scroll offset in
   // CSS pixels for the given ViewID.