[cc] Enable OneCopyRasterBufferPlaybackNormalThreadPriority by default.

28-days of Beta experiment revealed no regression:
go/onecopyrasterbufferplaybacknormalthreadpriority-beta-results

Bug: 1072756
Change-Id: Ib2e06e1e748073321ca37618b2466a2880b12ca5
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2485590
Auto-Submit: François Doray <fdoray@chromium.org>
Reviewed-by: vmpstr <vmpstr@chromium.org>
Commit-Queue: François Doray <fdoray@chromium.org>
Cr-Commit-Position: refs/heads/master@{#819662}

cc/raster/one_copy_raster_buffer_provider.cc

@@ -42,11 +42,11 @@ const int kMaxBytesPerCopyOperation = 1024 * 1024 * 4;
 
 // When enabled, OneCopyRasterBufferProvider::RasterBufferImpl::Playback() runs
 // at normal thread priority.
-// TODO(https://crbug.com/1072756): Enable by default and remove the feature
-// once experiments confirm that this prevents priority inversions.
+// TODO(crbug.com/1072756): Cleanup the feature when the Stable experiment is
+// complete, on November 25, 2020.
 const base::Feature kOneCopyRasterBufferPlaybackNormalThreadPriority{
     "OneCopyRasterBufferPlaybackNormalThreadPriority",
-    base::FEATURE_DISABLED_BY_DEFAULT};
+    base::FEATURE_ENABLED_BY_DEFAULT};
 
 }  // namespace