ozone: Let BGRA fullscreen overlays replace primary plane.

ui/ozone/platform/drm/gpu/hardware_display_plane_manager.cc

Index: ui/ozone/platform/drm/gpu/hardware_display_plane_manager.cc
diff --git a/ui/ozone/platform/drm/gpu/hardware_display_plane_manager.cc b/ui/ozone/platform/drm/gpu/hardware_display_plane_manager.cc
index 90147a893d8a2d83e4a56cf436956a6f0557a392..f972fa4bc4ade00c81aa5963a0dd0283f2fa8c82 100644
--- a/ui/ozone/platform/drm/gpu/hardware_display_plane_manager.cc
+++ b/ui/ozone/platform/drm/gpu/hardware_display_plane_manager.cc
@@ -234,7 +234,6 @@ bool HardwareDisplayPlaneManager::AssignOverlayPlanes(
   size_t plane_idx = 0;
   HardwareDisplayPlane* primary_plane = nullptr;
   gfx::Rect primary_display_bounds;
-  uint32_t primary_format;
   for (const auto& plane : overlay_list) {
     HardwareDisplayPlane* hw_plane =
         FindNextUnusedPlane(&plane_idx, crtc_index, plane);
@@ -265,12 +264,12 @@ bool HardwareDisplayPlaneManager::AssignOverlayPlanes(
     // it as primary. This reduces the no of planes which need to be read in
     // display controller side.
     if (primary_plane) {
-      bool needs_blending = true;
-      if (fourcc_format == DRM_FORMAT_XRGB8888)
-        needs_blending = false;
-      // TODO(kalyank): Check if we can move this optimization to
-      // DrmOverlayCandidatesHost.
-      if (!needs_blending && primary_format == fourcc_format &&
+      // TODO(dcastagna): Check if we can move this optimization to
+      // GLRenderer::ScheduleOverlays.
+      // Note that Chromium compositor promotes buffers to overlays (ARGB
+      // ones too) only if blending is not needed.
+      if ((fourcc_format == DRM_FORMAT_XRGB8888 ||
+           fourcc_format == DRM_FORMAT_ARGB8888) &&
           primary_display_bounds == plane.display_bounds) {
         ResetCurrentPlaneList(plane_list);
         hw_plane = primary_plane;
@@ -278,7 +277,6 @@ bool HardwareDisplayPlaneManager::AssignOverlayPlanes(
     } else {
       primary_plane = hw_plane;
       primary_display_bounds = plane.display_bounds;
-      primary_format = fourcc_format;
     }
 
     if (!SetPlaneData(plane_list, hw_plane, plane, crtc_id, fixed_point_rect,