Turn on FastBorderRadius by default on non-Mac platforms.

Bug: 967076

Change-Id: I099d7862e216ea656fccef800d38e3396b0a8668
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1761077
Commit-Queue: Chris Harrelson <chrishtr@chromium.org>
Reviewed-by: Mason Freed <masonfreed@chromium.org>
Cr-Commit-Position: refs/heads/master@{#689112}

cc/trees/property_tree.cc

@@ -1203,8 +1203,9 @@ bool EffectTree::ClippedHitTestRegionIsRectangle(int effect_id) const {
 bool EffectTree::HitTestMayBeAffectedByMask(int effect_id) const {
   const EffectNode* effect_node = Node(effect_id);
   for (; effect_node->id != kContentsRootNodeId;
-       effect_node = Node(effect_node->target_id)) {
-    if (effect_node->has_masking_child || effect_node->is_masked)
+       effect_node = Node(effect_node->parent_id)) {
+    if (!effect_node->rounded_corner_bounds.IsEmpty() ||
+        effect_node->has_masking_child || effect_node->is_masked)
       return true;
   }
   return false;

third_party/blink/common/features.cc

@@ -73,8 +73,16 @@ const base::Feature kDisplayLocking{"DisplayLocking",
 
 // Enable applying rounded corner masks via a GL shader rather than
 // a mask layer.
-const base::Feature kFastBorderRadius{"FastBorderRadius",
-                                      base::FEATURE_DISABLED_BY_DEFAULT};
+const base::Feature kFastBorderRadius {
+  "FastBorderRadius",
+#if defined(OS_MACOSX)
+      // A FastBorderRadiusMac experiment is rolling out separately for that
+      // platform, due to complications with CALayer overlay optimizations.
+      base::FEATURE_DISABLED_BY_DEFAULT
+#else
+      base::FEATURE_ENABLED_BY_DEFAULT
+#endif
+};
 
 // Enable LayoutNG.
 const base::Feature kLayoutNG{"LayoutNG", base::FEATURE_ENABLED_BY_DEFAULT};