Add methods for creating V8 extras-based ReadableStreams from C++

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

 // 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.
 
 #include "bindings/core/v8/ReadableStreamOperations.h"
 
 #include "bindings/core/v8/ExceptionState.h"
 #include "bindings/core/v8/ScriptState.h"
+#include "bindings/core/v8/ToV8.h"
 #include "bindings/core/v8/V8Binding.h"
+#include "bindings/core/v8/V8RecursionScope.h"
+#include "core/streams/UnderlyingSourceBase.h"
 
 namespace blink {
 
+ScriptValue ReadableStreamOperations::createReadableStream(ScriptState* scriptState, UnderlyingSourceBase* underlyingSource, ScriptValue strategy)
+{
+    ScriptState::Scope scope(scriptState);
+
+    v8::Local<v8::Value> jsUnderlyingSource = toV8(underlyingSource, scriptState);
+    v8::Local<v8::Value> jsStrategy = strategy.v8Value();
+
+    V8RecursionScope::MicrotaskSuppression mtsScope(scriptState->isolate());

[haraken, 2016/01/25 00:13:29]

Maybe it would make sense to create another version of v8CallExtraOrCrash for
calling an internal function.

- callV8ExtraFunction()
- callInternalV8ExtraFunction()

[domenic, 2016/02/02 22:59:55]

Aren't all V8 extra functions internal functions? At least that was my
intent---things you put on the V8 extras binding object should be browser code.

Maybe v8CallExtraOrCrash should use V8ScriptRunner::callInternalFunction instead
of callFunction?

+    v8::Local<v8::Value> args[] = { jsUnderlyingSource, jsStrategy };
+    v8::Local<v8::Value> jsStream = v8CallExtraOrCrash(scriptState, "createReadableStreamWithExternalController", args);
+
+    return ScriptValue(scriptState, jsStream);
+}
+
+ScriptValue ReadableStreamOperations::createCountQueuingStrategy(ScriptState* scriptState, size_t highWaterMark)
+{
+    ScriptState::Scope scope(scriptState);
+    v8::Isolate* isolate = scriptState->isolate();
+
+    v8::Local<v8::Value> args[] = { v8::Number::New(isolate, highWaterMark) };
+    v8::Local<v8::Value> jsStrategy = v8CallExtraOrCrash(scriptState, "createBuiltInCountQueuingStrategy", args);
+
+    return ScriptValue(scriptState, jsStrategy);
+}
+
 ScriptValue ReadableStreamOperations::getReader(ScriptState* scriptState, ScriptValue stream, ExceptionState& es)
 {
     ASSERT(isReadableStream(scriptState, stream));
 
     v8::TryCatch block(scriptState->isolate());
     v8::Local<v8::Value> args[] = { stream.v8Value() };
     ScriptValue result(scriptState, v8CallExtra(scriptState, "AcquireReadableStreamReader", args));
     if (block.HasCaught())
         es.rethrowV8Exception(block.Exception());
     return result;
@@ skipping 40 matching lines @@
 ScriptPromise ReadableStreamOperations::read(ScriptState* scriptState, ScriptValue reader)
 {
     ASSERT(isReadableStreamReader(scriptState, reader));
 
     v8::Local<v8::Value> args[] = { reader.v8Value() };
     return ScriptPromise::cast(scriptState, v8CallExtraOrCrash(scriptState, "ReadFromReadableStreamReader", args));
 }
 
 } // namespace blink