Add [CachedAccessor] attribute to cache (almost) constant accessors (window.document).

third_party/WebKit/Source/bindings/core/v8/V8PrivateProperty.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 V8PrivateProperty_h
 #define V8PrivateProperty_h
 
 #include "bindings/core/v8/ScopedPersistent.h"
 #include "bindings/core/v8/ScriptPromiseProperties.h"
 #include "bindings/core/v8/V8BindingMacros.h"
 #include "bindings/core/v8/V8PerIsolateData.h"
 #include "core/CoreExport.h"
 #include "wtf/Allocator.h"
 #include "wtf/PtrUtil.h"
 #include <memory>
 #include <v8.h>
 
 namespace blink {
 
 class ScriptState;
 class ScriptWrappable;
 
 // Apply |X| for each pair of (InterfaceName, PrivateKeyName).
-#define V8_PRIVATE_PROPERTY_FOR_EACH(X) \
-    X(CustomEvent, Detail) \
-    X(DOMException, Error) \
-    X(ErrorEvent, Error) \
-    X(IDBObserver, Callback) \
-    X(IntersectionObserver, Callback) \
-    X(MessageEvent, CachedData) \
-    X(MutationObserver, Callback) \
-    X(PerformanceObserver, Callback) \
+#define V8_PRIVATE_PROPERTY_FOR_EACH(X)   \
+    X(CustomEvent, Detail)                \
+    X(DOMException, Error)                \
+    X(ErrorEvent, Error)                  \
+    X(IDBObserver, Callback)              \
+    X(IntersectionObserver, Callback)     \
+    X(MessageEvent, CachedData)           \
+    X(MutationObserver, Callback)         \
+    X(PerformanceObserver, Callback)      \
     X(PrivateScriptRunner, IsInitialized) \
-    X(SameObject, NotificationActions) \
-    X(SameObject, NotificationData) \
-    X(SameObject, NotificationVibrate) \
-    X(V8NodeFilterCondition, Filter)
+    X(SameObject, NotificationActions)    \
+    X(SameObject, NotificationData)       \
+    X(SameObject, NotificationVibrate)    \
+    X(V8NodeFilterCondition, Filter)      \
+    X(Window, Document)

[haraken, 2016/09/20 14:15:03]

I'd prefer X(Window, DocumentCachedAccessor) to avoid conflict with other
private properties.

(In long term, we might want to auto-generate the private properties for cached
accessors with the IDL compiler.)

 
 // The getter's name for a private property.
 #define V8_PRIVATE_PROPERTY_GETTER_NAME(InterfaceName, PrivateKeyName) \
     get##InterfaceName##PrivateKeyName
 
 // The member variable's name for a private property.
 #define V8_PRIVATE_PROPERTY_MEMBER_NAME(InterfaceName, PrivateKeyName) \
     m_symbol##InterfaceName##PrivateKeyName
 
 // The string used to create a private symbol.  Must be unique per V8 instance.
@@ skipping 46 matching lines @@
             if (v8Call(object->GetPrivate(context, m_privateSymbol), value))
                 return value;
             return v8::Local<v8::Value>();
         }
 
         bool set(v8::Local<v8::Context> context, v8::Local<v8::Object> object, v8::Local<v8::Value> value) const
         {
             return v8CallBoolean(object->SetPrivate(context, m_privateSymbol, value));
         }
 
+        v8::Local<v8::Private> getPrivate()
+        {
+            return m_privateSymbol;
+        }
+
     private:
         friend class V8PrivateProperty;
         // The following classes are exceptionally allowed to call to
         // getFromMainWorld.
         friend class V8CustomEvent;
         friend class V8ServiceWorkerMessageEventInternal;
 
         explicit Symbol(v8::Local<v8::Private> privateSymbol)
             : m_privateSymbol(privateSymbol) { }
 
@@ skipping 37 matching lines @@
 
 #define V8_PRIVATE_PROPERTY_DECLARE_MEMBER(InterfaceName, KeyName) \
     ScopedPersistent<v8::Private> V8_PRIVATE_PROPERTY_MEMBER_NAME(InterfaceName, KeyName); // NOLINT(readability/naming/underscores)
     V8_PRIVATE_PROPERTY_FOR_EACH(V8_PRIVATE_PROPERTY_DECLARE_MEMBER)
 #undef V8_PRIVATE_PROPERTY_DECLARE_MEMBER
 };
 
 } // namespace blink
 
 #endif // V8PrivateProperty_h