base::mac::IsOSSierra() -> base::mac::IsOS10_12(), etc.

third_party/WebKit/Source/platform/mac/VersionUtilMac.h

Index: third_party/WebKit/Source/platform/mac/VersionUtilMac.h
diff --git a/third_party/WebKit/Source/platform/mac/VersionUtilMac.h b/third_party/WebKit/Source/platform/mac/VersionUtilMac.h
index ccff619df8d9d466d8dc4d1e3271d87e4008d04b..079825f11d010d749beadf0a6d64e2c466350008 100644
--- a/third_party/WebKit/Source/platform/mac/VersionUtilMac.h
+++ b/third_party/WebKit/Source/platform/mac/VersionUtilMac.h
@@ -7,16 +7,26 @@
 
 #include "platform/PlatformExport.h"
 
+#include <AvailabilityMacros.h>
+
 namespace blink {
 
-// Mavericks is Mac OS X 10.9, Darwin 13.
-PLATFORM_EXPORT bool IsOSMavericks();
+namespace internal {
+
+PLATFORM_EXPORT int MacOSXMinorVersion();
+
+template <int V, int ID>
+constexpr bool IsOS()
+{
+    return MAC_OS_X_VERSION_MIN_REQUIRED <= ID && MacOSXMinorVersion() == V;
+}
 
-// Yosemite is Mac OS X 10.10, Darwin 14.
-PLATFORM_EXPORT bool IsOSYosemite();
+} // namespace internal
 
-// El Capitan is Mac OS X 10.11, Darwin 15.
-PLATFORM_EXPORT bool IsOSElCapitan();
+const auto IsOS10_9 = internal::IsOS<9, 1090>;
+const auto IsOS10_10 = internal::IsOS<10, 101000>;
+const auto IsOS10_11 = internal::IsOS<11, 101100>;
+const auto IsOS10_12 = internal::IsOS<12, 101200>;
 
 } // namespace blink