tor-browser

commit 8bffb8f28dadfe6a26ecc5ff99c0a9a9182dd774
parent 8f6791c0b7e3ed49e19577f3cb3c71badfe33e53
Author: Markus Stange <mstange.moz@gmail.com>
Date:   Thu,  2 Oct 2025 20:49:14 +0000

Bug 1987007 - Keep doing reftest snapshots in the parent, even though we can now do them in the GPU process. r=bradwerth

Asking the parent lets us detect bugs in the cross-process synchronization of
the layer trees.

Differential Revision: https://phabricator.services.mozilla.com/D267279

Diffstat:
M
gfx/layers/NativeLayerCA.h
 | 
5
+++++
M
gfx/layers/NativeLayerCA.mm
 | 
5
+++++
M
gfx/layers/NativeLayerRootRemoteMacChild.h
 | 
26
++++++++++++++++++++++++--
M
gfx/layers/NativeLayerRootRemoteMacChild.mm
 | 
2
+-

4 files changed, 35 insertions(+), 3 deletions(-)
diff --git a/gfx/layers/NativeLayerCA.h b/gfx/layers/NativeLayerCA.h
@@ -77,6 +77,11 @@ class SnapshotterCADelegate {
   virtual ~SnapshotterCADelegate();
 
   virtual float BackingScale() const { return 1.0f; }
+  virtual bool DoCustomReadbackForReftestsIfDesired(
+      const gfx::IntSize& aReadbackSize, gfx::SurfaceFormat aReadbackFormat,
+      const Range<uint8_t>& aReadbackBuffer) {
+    return false;
+  }
   virtual void UpdateSnapshotterLayers(CALayer* aRootCALayer) = 0;
   virtual void OnSnapshotterDestroyed(
       NativeLayerRootSnapshotterCA* aSnapshotter) {}
diff --git a/gfx/layers/NativeLayerCA.mm b/gfx/layers/NativeLayerCA.mm
@@ -790,6 +790,11 @@ void NativeLayerRootSnapshotterCA::UpdateSnapshot(const IntSize& aSize) {
 bool NativeLayerRootSnapshotterCA::ReadbackPixels(
     const IntSize& aReadbackSize, SurfaceFormat aReadbackFormat,
     const Range<uint8_t>& aReadbackBuffer) {
+  if (mDelegate->DoCustomReadbackForReftestsIfDesired(
+          aReadbackSize, aReadbackFormat, aReadbackBuffer)) {
+    return true;
+  }
+
   if (aReadbackFormat != SurfaceFormat::B8G8R8A8) {
     return false;
   }
diff --git a/gfx/layers/NativeLayerRootRemoteMacChild.h b/gfx/layers/NativeLayerRootRemoteMacChild.h
@@ -59,6 +59,12 @@ class NativeLayerRootRemoteMacChild final : public NativeLayerRoot {
     virtual void UpdateSnapshotterLayers(CALayer* aRootCALayer) override {
       mLayerRoot->CommitForSnapshot(aRootCALayer);
     }
+    virtual bool DoCustomReadbackForReftestsIfDesired(
+        const gfx::IntSize& aReadbackSize, gfx::SurfaceFormat aReadbackFormat,
+        const Range<uint8_t>& aReadbackBuffer) override {
+      return mLayerRoot->ReadbackPixelsFromParent(
+          aReadbackSize, aReadbackFormat, aReadbackBuffer);
+    }
     virtual void OnSnapshotterDestroyed(
         NativeLayerRootSnapshotterCA* aSnapshotter) override {
       mLayerRoot->OnNativeLayerRootSnapshotterDestroyed(aSnapshotter);
@@ -74,8 +80,24 @@ class NativeLayerRootRemoteMacChild final : public NativeLayerRoot {
   bool mNativeLayersChanged = false;
   bool mNativeLayersChangedForSnapshot = false;
 
-  bool ReadbackPixels(const gfx::IntSize& aSize, gfx::SurfaceFormat aFormat,
-                      const Range<uint8_t>& aBuffer);
+  // Send a sync message to the parent to get the window pixels.
+  // Used for reftests.
+  //
+  // This is different from what we do for "window recorder" and
+  // "profiler screenshot" snapshotting, where we do the snapshotting
+  // within the GPU process, using CARenderer on a CALayer tree we
+  // construct within the GPU process.
+  //
+  // Here's why we have two different snapshotting paths:
+  // - Profiler screenshots and window recording care about minimal overhead
+  //   and need to minimize blocking on the GPU.
+  // - Reftests care about catching bugs, and don't need maximum performance.
+  //   By doing the readback in the parent, we can catch more bugs, for
+  //   example bugs in the IPC serialization of layer updates and how those
+  //   updates are applied on the parent side.
+  bool ReadbackPixelsFromParent(const gfx::IntSize& aSize,
+                                gfx::SurfaceFormat aFormat,
+                                const Range<uint8_t>& aBuffer);
 };
 
 }  // namespace layers
diff --git a/gfx/layers/NativeLayerRootRemoteMacChild.mm b/gfx/layers/NativeLayerRootRemoteMacChild.mm
@@ -153,7 +153,7 @@ void NativeLayerRootRemoteMacChild::CommitForSnapshot(CALayer* aRootCALayer) {
   mNativeLayersChangedForSnapshot = false;
 }
 
-bool NativeLayerRootRemoteMacChild::ReadbackPixels(
+bool NativeLayerRootRemoteMacChild::ReadbackPixelsFromParent(
     const gfx::IntSize& aSize, gfx::SurfaceFormat aFormat,
     const Range<uint8_t>& aBuffer) {
   // In this process we only have the pixels of the individual layers,