Add a utility class to call stream methods implemented with v8 extras.

third_party/WebKit/Source/bindings/core/v8/ReadableStreamOperations.h

+// Copyright 2015 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 ReadableStreamOperations_h
+#define ReadableStreamOperations_h
+
+#include "bindings/core/v8/ScriptPromise.h"
+#include "bindings/core/v8/ScriptValue.h"
+#include <v8.h>
+
+namespace blink {
+
+class ScriptState;
+
+// This class has various methods for ReadableStream[Reader] implemented with
+// V8 Extras.
+// All methods should be called in an appropriate V8 context. All v8 handle
+// arguments must not be empty.
+class CORE_EXPORT ReadableStreamOperations {

[domenic, 2015/12/02 17:53:03]

Why a class full of public methods instead of a namespace full of functions?

[yhirano, 2015/12/03 11:18:29]

I'm hearing opinions on blink-dev.

+    STATIC_ONLY(ReadableStreamOperations);
+public:
+    // AcquireReadableStreamReader
+    // This function assumes |isReadableStream(stream)|.
+    // Returns an empty value and throws an error (in the V8 context) when

[domenic, 2015/12/02 17:53:03]

Should this be handled using an ExceptionState& instead?

[yhirano, 2015/12/03 11:18:29]

Done.

+    // errored.
+    static ScriptValue getReader(ScriptState*, v8::Local<v8::Value> stream);
+
+    // IsReadableStream
+    static bool isReadableStream(ScriptState*, v8::Local<v8::Value>);
+
+    // IsReadableStreamDisturbed
+    // This function assumes |isReadableStream(stream)|.
+    static bool isDisturbed(ScriptState*, v8::Local<v8::Value> stream);
+
+    // IsReadableStreamLocked
+    // This function assumes |isReadableStream(stream)|.
+    static bool isLocked(ScriptState*, v8::Local<v8::Value> stream);
+
+    // IsReadableStreamReader
+    static bool isReadableStreamReader(ScriptState*, v8::Local<v8::Value>);
+
+    // ReadFromReadableStreamReader
+    // This function assumes |isReadableStreamReader(reader)|.
+    static ScriptPromise read(ScriptState*, v8::Local<v8::Value> reader);
+};
+
+} // namespace blink
+
+#endif // ReadableStreamOperations_h