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

third_party/WebKit/Source/bindings/core/v8/V8BindingMacros.h

Index: third_party/WebKit/Source/bindings/core/v8/V8BindingMacros.h
diff --git a/third_party/WebKit/Source/bindings/core/v8/V8BindingMacros.h b/third_party/WebKit/Source/bindings/core/v8/V8BindingMacros.h
index 3b55b06f35914fa096a57ab701b88beba9dff105..c4ca60586ae1f8a165efc57b82d0c5b102091db6 100644
--- a/third_party/WebKit/Source/bindings/core/v8/V8BindingMacros.h
+++ b/third_party/WebKit/Source/bindings/core/v8/V8BindingMacros.h
@@ -31,6 +31,10 @@
 #ifndef V8BindingMacros_h
 #define V8BindingMacros_h
 
+#include "bindings/core/v8/ScriptState.h"
+#include "bindings/core/v8/ScriptValue.h"
+#include <v8.h>
+
 namespace blink {
 
 // type is an instance of class template V8StringResource<>,
@@ -103,6 +107,28 @@ inline v8::Local<T> v8CallOrCrash(v8::MaybeLocal<T> maybeLocal)
     return maybeLocal.ToLocalChecked();
 }
 
+v8::MaybeLocal<v8::Value> v8CallExtra(ScriptState* scriptState, const char* name, size_t numArgs, v8::Local<v8::Value>* args)
+{
+    v8::Isolate* isolate = scriptState->isolate();
+    v8::Local<v8::Context> context = scriptState->context();
+    v8::Local<v8::Value> undefined = v8::Undefined(isolate);
+    v8::Local<v8::Value> functionValue = scriptState->getFromExtrasExports(name).v8Value();
+    v8::Local<v8::Function> function = functionValue.As<v8::Function>();
+    return function->Call(context, undefined, numArgs, args);
+}
+
+template <size_t N>
+v8::MaybeLocal<v8::Value> v8CallExtra(ScriptState* scriptState, const char* name, v8::Local<v8::Value>(&args)[N])
+{
+    return v8CallExtra(scriptState, name, N, args);
+}
+
+template <size_t N>
+v8::Local<v8::Value> v8CallExtraOrCrash(ScriptState* scriptState, const char* name, v8::Local<v8::Value>(&args)[N])
+{
+    return v8CallOrCrash(v8CallExtra(scriptState, name, N, args));
+}
+
 // The last "else" is to avoid dangling else problem.
 #define V8_CALL(outVariable, handle, methodCall, failureExpression)                \
     if (handle.IsEmpty() || !v8Call(handle->methodCall, outVariable)) { \