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

Source/core/testing/Internals.cpp

Index: Source/core/testing/Internals.cpp
diff --git a/Source/core/testing/Internals.cpp b/Source/core/testing/Internals.cpp
index 6f84a6b09302e5d3bf85f6c02a28aae1307d399a..069b81257db6df3e52063db3a75c2337321c89da 100644
--- a/Source/core/testing/Internals.cpp
+++ b/Source/core/testing/Internals.cpp
@@ -117,6 +117,7 @@
 #include "core/paint/DeprecatedPaintLayer.h"
 #include "core/plugins/testing/DictionaryPluginPlaceholder.h"
 #include "core/plugins/testing/DocumentFragmentPluginPlaceholder.h"
+#include "core/streams/ReadableStream2.h"
 #include "core/testing/DictionaryTest.h"
 #include "core/testing/GCObservation.h"
 #include "core/testing/InternalRuntimeFlags.h"
@@ -192,9 +193,9 @@ static SpellCheckRequester* spellCheckRequester(Document* document)
 
 const char* Internals::internalsId = "internals";
 
-Internals* Internals::create(Document* document)
+Internals* Internals::create(ScriptState* scriptState)
 {
-    return new Internals(document);
+    return new Internals(scriptState);
 }
 
 Internals::~Internals()
@@ -220,9 +221,26 @@ void Internals::resetToConsistentState(Page* page)
     page->deprecatedLocalMainFrame()->view()->clear();
 }
 
-Internals::Internals(Document* document)
-    : ContextLifecycleObserver(document)
+namespace {
+
+class TestUnderlyingSource : public UnderlyingSourceBase {
+public:
+    ScriptPromise start(ScriptState* scriptState) override
+    {
+        controller().enqueue("a");
+        controller().enqueue("b");
+        controller().close();
+        return UnderlyingSourceBase::start(scriptState);
+    };
+};
+
+} // namespace
+
+Internals::Internals(ScriptState* scriptState)
+    : ContextLifecycleObserver(scriptState->executionContext())
     , m_runtimeFlags(InternalRuntimeFlags::create())
+    , m_readableStream(new ReadableStream2(scriptState, new TestUnderlyingSource(),
+        ReadableStream2::createCountQueuingStrategy(scriptState, 1024.0)))
 {
 }
 
@@ -2370,4 +2388,9 @@ ClientRectList* Internals::focusRingRects(Element* element)
     return ClientRectList::create(rects);
 }
 
+ScriptValue Internals::readableStream()
+{
+    return m_readableStream->scriptValue();
+}
+
 } // namespace blink