Add UseCounter for non-standard getComputedStyle(e).cssX behaviour

Source/bindings/core/v8/custom/V8CSSStyleDeclarationCustom.cpp

 /*
  * Copyright (C) 2007-2011 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 22 matching lines @@
 
 #include "bindings/core/v8/ExceptionState.h"
 #include "bindings/core/v8/V8Binding.h"
 #include "core/CSSPropertyNames.h"
 #include "core/css/CSSPrimitiveValue.h"
 #include "core/css/CSSPropertyMetadata.h"
 #include "core/css/CSSStyleDeclaration.h"
 #include "core/css/CSSValue.h"
 #include "core/css/parser/CSSParser.h"
 #include "core/events/EventTarget.h"
+#include "core/frame/UseCounter.h"
 #include "wtf/ASCIICType.h"
 #include "wtf/PassRefPtr.h"
 #include "wtf/RefPtr.h"
 #include "wtf/StdLibExtras.h"
 #include "wtf/Vector.h"
 #include "wtf/text/StringBuilder.h"
 #include "wtf/text/StringConcatenate.h"
 
 using namespace WTF;
 
@@ skipping 23 matching lines @@
         if (propertyName[i] != prefix[i])
             return false;
     }
     return false;
 }
 
 struct CSSPropertyInfo {
     CSSPropertyID propID;
 };
 
-static CSSPropertyID cssResolvedPropertyID(const String& propertyName)
+static CSSPropertyID cssResolvedPropertyID(const String& propertyName, v8::Isolate* isolate)
 {
     unsigned length = propertyName.length();
     if (!length)
         return CSSPropertyInvalid;
 
     StringBuilder builder;
     builder.reserveCapacity(length);
 
     unsigned i = 0;
     bool hasSeenDash = false;
 
-    if (hasCSSPropertyNamePrefix(propertyName, "css"))
-        i += 3;
-    else if (hasCSSPropertyNamePrefix(propertyName, "webkit"))
+    if (hasCSSPropertyNamePrefix(propertyName, "css")) {
+        // getComputedStyle("id").cssX is a non-standard behaviour
+        // Measure this behaviour as CSSXGetComputedStyleQueries.
+        UseCounter::count(callingExecutionContext(isolate), UseCounter::CSSXGetComputedStyleQueries);
+        return CSSPropertyInvalid;

[haraken, 2014/10/03 14:07:27]

Are you planning to actually change the behavior before getting enough user
counter numbers?

We normally change the behavior after confirming that the use counter numbers
are small enough.

[Sunil Ratnu, 2014/10/03 14:22:32]

Yeah correct, that is the usual flow. I might have misread the bug (usecounter
and remove). The bug description must have meant "UseCounter and then eventually
remove".
I think we should stay with using Counters first and then removing the
behaviour. If you say so, I will upload a new patch with just using counters.
Your final take?

+    }
+    if (hasCSSPropertyNamePrefix(propertyName, "webkit"))
         builder.append('-');
     else if (isASCIIUpper(propertyName[0]))
         return CSSPropertyInvalid;
 
     bool hasSeenUpper = isASCIIUpper(propertyName[i]);
 
     builder.append(toASCIILower(propertyName[i++]));
 
     for (; i < length; ++i) {
         UChar c = propertyName[i];
@@ skipping 18 matching lines @@
 
 // When getting properties on CSSStyleDeclarations, the name used from
 // Javascript and the actual name of the property are not the same, so
 // we have to do the following translation. The translation turns upper
 // case characters into lower case characters and inserts dashes to
 // separate words.
 //
 // Example: 'backgroundPositionY' -> 'background-position-y'
 //
 // Also, certain prefixes such as 'css-' are stripped.
-static CSSPropertyInfo* cssPropertyInfo(v8::Handle<v8::String> v8PropertyName)
+static CSSPropertyInfo* cssPropertyInfo(v8::Handle<v8::String> v8PropertyName, v8::Isolate* isolate)
 {
     String propertyName = toCoreString(v8PropertyName);
     typedef HashMap<String, CSSPropertyInfo*> CSSPropertyInfoMap;
     DEFINE_STATIC_LOCAL(CSSPropertyInfoMap, map, ());
     CSSPropertyInfo* propInfo = map.get(propertyName);
     if (!propInfo) {
         propInfo = new CSSPropertyInfo();
-        propInfo->propID = cssResolvedPropertyID(propertyName);
+        propInfo->propID = cssResolvedPropertyID(propertyName, isolate);
         map.add(propertyName, propInfo);
     }
     if (!propInfo->propID)
         return 0;
     ASSERT(CSSPropertyMetadata::isEnabledProperty(propInfo->propID));
     return propInfo;
 }
 
 void V8CSSStyleDeclaration::namedPropertyEnumeratorCustom(const v8::PropertyCallbackInfo<v8::Array>& info)
 {
@@ skipping 18 matching lines @@
         properties->Set(v8::Integer::New(info.GetIsolate(), i), v8String(info.GetIsolate(), key));
     }
 
     v8SetReturnValue(info, properties);
 }
 
 void V8CSSStyleDeclaration::namedPropertyQueryCustom(v8::Local<v8::String> v8Name, const v8::PropertyCallbackInfo<v8::Integer>& info)
 {
     // NOTE: cssPropertyInfo lookups incur several mallocs.
     // Successful lookups have the same cost the first time, but are cached.
-    if (cssPropertyInfo(v8Name)) {
+    if (cssPropertyInfo(v8Name, info.GetIsolate())) {
         v8SetReturnValueInt(info, 0);
         return;
     }
 }
 
 void V8CSSStyleDeclaration::namedPropertyGetterCustom(v8::Local<v8::String> name, const v8::PropertyCallbackInfo<v8::Value>& info)
 {
     // First look for API defined attributes on the style declaration object.
     if (info.Holder()->HasRealNamedCallbackProperty(name))
         return;
 
     // Search the style declaration.
-    CSSPropertyInfo* propInfo = cssPropertyInfo(name);
+    CSSPropertyInfo* propInfo = cssPropertyInfo(name, info.GetIsolate());
 
     // Do not handle non-property names.
     if (!propInfo)
         return;
 
     CSSStyleDeclaration* impl = V8CSSStyleDeclaration::toImpl(info.Holder());
     RefPtrWillBeRawPtr<CSSValue> cssValue = impl->getPropertyCSSValueInternal(static_cast<CSSPropertyID>(propInfo->propID));
     if (cssValue) {
         v8SetReturnValueStringOrNull(info, cssValue->cssText(), info.GetIsolate());
         return;
     }
 
     String result = impl->getPropertyValueInternal(static_cast<CSSPropertyID>(propInfo->propID));
     v8SetReturnValueString(info, result, info.GetIsolate());
 }
 
 void V8CSSStyleDeclaration::namedPropertySetterCustom(v8::Local<v8::String> name, v8::Local<v8::Value> value, const v8::PropertyCallbackInfo<v8::Value>& info)
 {
     CSSStyleDeclaration* impl = V8CSSStyleDeclaration::toImpl(info.Holder());
-    CSSPropertyInfo* propInfo = cssPropertyInfo(name);
+    CSSPropertyInfo* propInfo = cssPropertyInfo(name, info.GetIsolate());
     if (!propInfo)
         return;
 
     TOSTRING_VOID(V8StringResource<TreatNullAsNullString>, propertyValue, value);
     ExceptionState exceptionState(ExceptionState::SetterContext, getPropertyName(static_cast<CSSPropertyID>(propInfo->propID)), "CSSStyleDeclaration", info.Holder(), info.GetIsolate());
     impl->setPropertyInternal(static_cast<CSSPropertyID>(propInfo->propID), propertyValue, false, exceptionState);
 
     if (exceptionState.throwIfNeeded())
         return;
 
     v8SetReturnValue(info, value);
 }
 
 } // namespace blink