Fix RGBA data VideoFrame copyTo

https://bugs.webkit.org/show_bug.cgi?id=247717
rdar://102160471

Reviewed by Eric Carlson.

* Source/WebCore/platform/graphics/cv/VideoFrameCV.mm:
(WebCore::VideoFrame::copyTo):
Copy the number of bytes and not the number of pixels.

Canonical link: https://commits.webkit.org/256534@main

Source/WebCore/platform/graphics/cv/VideoFrameCV.mm

@@ -354,7 +354,9 @@ static void copyPlane(uint8_t* destination, const uint8_t* source, uint64_t sour
         ComputedPlaneLayout planeLayout;
         if (!computedPlaneLayout.isEmpty())
             planeLayout = computedPlaneLayout[0];
-        auto planeLayouts = copyRGBData(span, planeLayout, this->pixelBuffer(), [](auto* destination, auto* source, size_t pixelCount) {
+        auto planeLayouts = copyRGBData(span, planeLayout, this->pixelBuffer(), [](auto* destination, auto* source, size_t byteLength) {
+            ASSERT(!(byteLength % 4));
+            auto pixelCount = byteLength / 4;
             size_t i = 0;
             while (pixelCount-- > 0) {
                 // ARGB -> RGBA.
@@ -373,8 +375,9 @@ static void copyPlane(uint8_t* destination, const uint8_t* source, uint64_t sour
         ComputedPlaneLayout planeLayout;
         if (!computedPlaneLayout.isEmpty())
             planeLayout = computedPlaneLayout[0];
-        auto planeLayouts = copyRGBData(span, planeLayout, this->pixelBuffer(), [](auto* destination, auto* source, size_t pixelCount) {
-            std::memcpy(destination, source, pixelCount * 4);
+
+        auto planeLayouts = copyRGBData(span, planeLayout, this->pixelBuffer(), [](auto* destination, auto* source, size_t byteLength) {
+            std::memcpy(destination, source, byteLength);
         });
         callback(WTFMove(planeLayouts));
         return;