Revert of Added api_methods flag to CSSProperties.json5.

third_party/WebKit/Source/core/css/properties/CSSPropertyAPI.h

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CSSPropertyAPI_h
 #define CSSPropertyAPI_h
 
 #include "core/CSSPropertyNames.h"
 #include "wtf/Allocator.h"
 
 namespace blink {
 
 class CSSValue;
 class CSSParserContext;
 class CSSParserTokenRange;
 
 // We will use this API to represent all functions used for property-specific
 // logic inside the blink style engine. All specific properties are subclasses
 // of CSSPropertyAPI.
 //
-// To add a new implementation of this API for a property:
-// - Make a class that implements CSSPropertyAPI.
-// - For each method that you wish to implement in this class, add this method
-//   name to the api_methods flag in CSSProperties.json5.
-// - Implement these methods in the .cpp file.
+// To add a new property using this API:
+// - Make a class that implements CSSPropertyAPI, and implement the static
+//   methods.
+// - Update the cssPropertyDescriptors array in CSSPropertyDescriptor.cpp to
+//   call GET_DESCRIPTOR(classname).
 //
-// To add new functions to this API:
-// - Add the function to the struct below.
-// - Add the function to CSSPropertyAPIFiles.h.tmpl template file, surrounded
-//   with an {% if "methodName" in implementedMethods %} check.
-// - Add the function name to the valid_methods array in
-//   make_css_property_apis.py.
-// - Add function to the initializer list in the cssPropertyDescriptors array
-//   in CSSPropertyDescriptor.cpp.tmpl, and add a nullptr to the invalid
-//   CSSPropertyDescriptor.
+// To add new functions using this API:
+// - New functions and static variables can be added in this class. A default
+//   implementation of functions can optionally be provided.
+// - When adding new functions, also add them to GET_DESCRIPTOR, and the get()
+//   method in CSSPropertyDescriptors.cpp, and the descriptor struct in
+//   CSSPropertyDescriptor.h.
 class CSSPropertyAPI {
   STATIC_ONLY(CSSPropertyAPI);
 
  public:
   // Parses a single CSS property and returns the corresponding CSSValue. If the
   // input is invalid it returns nullptr.
   static const CSSValue* parseSingleValue(CSSParserTokenRange&,
-                                          const CSSParserContext*) {
-    // No code should reach here, since properties either have their own
-    // implementations of this method or store nullptr in their descriptor.
-    NOTREACHED();
-    return nullptr;
-  }
+                                          const CSSParserContext*);
 };
 
 }  // namespace blink
 
 #endif  // CSSPropertyAPI_h