cef_host: point the resize capture refresh at CEF issue #3826

packages/flutter_cef_macos/CHANGELOG.md

@@ -4,8 +4,9 @@
   the new size (up to about 4 s), most often mid-way through an animated device
   switch. CEF paints by capturing the view: the renderer's first frame at the
   new size was captured at the old size, and the capturer's own retries were
-  turned away until the stall fallback kicked in. `cef_host` now asks for a
-  fresh capture every 100 ms while a resize waits for its paint.
+  turned away until the stall fallback kicked in (CEF issue #3826, fixed in
+  CEF 8037+). `cef_host` now asks for a fresh capture every 100 ms while a
+  resize waits for its paint.
   `device_frame` no longer needs the stall fallback (it did in 1 to 12 of 30
   switches). The prebuilt must be republished.
 * Fix: a view could stop painting for good after a resize that changed the

packages/flutter_cef_macos/native/cef_host/browser_ops.mm

@@ -402,13 +402,15 @@ void DoSetVisible(const std::shared_ptr<Slot>& slot, bool visible) {
 // size of the renderer's last activated frame. When the renderer's frame at the
 // new size activates, it is captured at the OLD size, and only then does CEF set
 // the new capture size. The capture that change asks for is rate-limited (one
-// was just taken), and the capturer's own retries go through a stricter check
-// (nothing pending, no recent animation) that can turn them all away. A page
-// with nothing else changing gives it no damage either, so no paint at the new
-// size came until the stall kick. Invalidate asks for a capture the way a
-// compositor update does, which isn't subject to that check. The one at the
-// start of a resize comes too early, so ask again every kResizeRefreshMs until
-// the paint arrives.
+// was just taken), and the capturer's own retries only capture when no capture
+// is pending. Chromium leaves a dropped capture counted as pending, so after one
+// drop those retries never capture again (CEF issue #3826). A page with nothing
+// else changing gives it no damage either, so no paint at the new size came
+// until the stall kick. Invalidate asks for a capture the way a compositor
+// update does, which isn't subject to that check. The one at the start of a
+// resize comes too early, so ask again every kResizeRefreshMs until the paint
+// arrives. CEF fixed the bookkeeping in viz_capture_3826.patch (branch 8037 and
+// later); on such a CEF this refresh is no longer needed.
 namespace {
 constexpr int kResizeRefreshMs = 100;
 constexpr int kResizePaintWaitMs = 1000;