Add documentation for platform/bindings

third_party/WebKit/Source/platform/bindings/V8ValueCache.h

 /*
  * Copyright (C) 2009 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:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 56 matching lines @@
   }
 
   static void OnWeakCallback(const v8::WeakCallbackInfo<WeakCallbackDataType>&);
 
   static void Dispose(v8::Isolate*,
                       v8::Global<v8::String> value,
                       StringImpl* key);
   static void DisposeWeak(const v8::WeakCallbackInfo<WeakCallbackDataType>&);
 };
 
+// String cache helps convert WTF strings (StringImpl*) into v8 strings by
+// only creating a v8::String for a particular StringImpl* once and caching it
+// for future use. It is held by and can be retrieved from V8PerIsolateData.

[haraken, 2017/04/29 02:39:11]

Add a comment about how the cache is maintained (when the entry is evicted, when
the cache is cleared).

[adithyas, 2017/05/01 17:41:16]

Done.

 class PLATFORM_EXPORT StringCache {
   USING_FAST_MALLOC(StringCache);
   WTF_MAKE_NONCOPYABLE(StringCache);
 
  public:
   explicit StringCache(v8::Isolate* isolate) : string_cache_(isolate) {}
 
   v8::Local<v8::String> V8ExternalString(v8::Isolate* isolate,
                                          StringImpl* string_impl) {
     DCHECK(string_impl);
@@ skipping 27 matching lines @@
 
   // Note: RefPtr is a must as we cache by StringImpl* equality, not identity
   // hence lastStringImpl might be not a key of the cache (in sense of identity)
   // and hence it's not refed on addition.
   RefPtr<StringImpl> last_string_impl_;
 };
 
 }  // namespace blink
 
 #endif  // V8ValueCache_h