Implement support for the 'transform-box' property

third_party/WebKit/Source/core/frame/UseCounter.cpp

Index: third_party/WebKit/Source/core/frame/UseCounter.cpp
diff --git a/third_party/WebKit/Source/core/frame/UseCounter.cpp b/third_party/WebKit/Source/core/frame/UseCounter.cpp
index 96e87a2d592688475d7d6cc8fc562022536b98ce..6c363695c2ef34a4f9d0a9ca6274b69d8ad3ca28 100644
--- a/third_party/WebKit/Source/core/frame/UseCounter.cpp
+++ b/third_party/WebKit/Source/core/frame/UseCounter.cpp
@@ -46,7 +46,7 @@ int totalPagesMeasuredCSSSampleId() {
 }
 
 // Make sure update_use_counter_css.py was run which updates histograms.xml.
-constexpr int kMaximumCSSSampleId = 558;
+constexpr int kMaximumCSSSampleId = 559;
 
 }  // namespace
 
@@ -1085,6 +1085,8 @@ int UseCounter::mapCSSPropertyIdToCSSSampleIdForHistogram(
       return 557;
     case CSSPropertyPlaceItems:
       return 558;
+    case CSSPropertyTransformBox:
+      return 559;
     // 1. Add new features above this line (don't change the assigned numbers of
     // the existing items).
     // 2. Update kMaximumCSSSampleId with the new maximum value.