Add base class ReadableStreamController

This CL aims to add polymorphism to the readable stream controller
classes. In particular, it adds a new base class called
ReadableStreamController, and the ReadableStreamDefaultController and
ReadableByteStreamController classes inherit PullSteps() and
CancelSteps() from the ReadableStreamController.

This is based on the approach discussed in
https://docs.google.com/document/d/1rvKpGjppeqRSWntokY-ft_hU2i2us8gis6zgrrLWSTI/view

Bug: 614302
Change-Id: I58439e52e43b525cadbb1a9d36dd950005a7c32c
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2531794
Commit-Queue: Nidhi Jaju <nidhijaju@google.com>
Reviewed-by: Adam Rice <ricea@chromium.org>
Reviewed-by: Yutaka Hirano <yhirano@chromium.org>
Cr-Commit-Position: refs/heads/master@{#827038}

third_party/blink/renderer/core/streams/build.gni

@@ -23,6 +23,7 @@ blink_core_sources_streams = [
   "readable_stream_byob_reader.h",
   "readable_stream_byob_request.cc",
   "readable_stream_byob_request.h",
+  "readable_stream_controller.h",
   "readable_stream_default_controller.cc",
   "readable_stream_default_controller.h",
   "readable_stream_default_controller_with_script_scope.cc",

third_party/blink/renderer/core/streams/readable_byte_stream_controller.cc

@@ -5,6 +5,7 @@
 #include "third_party/blink/renderer/core/streams/readable_byte_stream_controller.h"
 
 #include "third_party/blink/renderer/core/streams/readable_stream_byob_request.h"
+#include "third_party/blink/renderer/core/streams/stream_promise_resolver.h"
 #include "third_party/blink/renderer/core/typed_arrays/dom_array_buffer_view.h"
 #include "third_party/blink/renderer/platform/bindings/exception_state.h"
 #include "third_party/blink/renderer/platform/bindings/script_state.h"
@@ -50,6 +51,29 @@ void ReadableByteStreamController::error(ScriptState* script_state,
   return;
 }
 
+//
+// Readable byte stream controller internal methods
+//
+
+v8::Local<v8::Promise> ReadableByteStreamController::CancelSteps(
+    ScriptState* script_state,
+    v8::Local<v8::Value> reason) {
+  ExceptionState exception_state(script_state->GetIsolate(),
+                                 ExceptionState::kExecutionContext, nullptr,
+                                 nullptr);
+  ThrowUnimplemented(exception_state);
+  return v8::Local<v8::Promise>();
+}
+
+StreamPromiseResolver* ReadableByteStreamController::PullSteps(
+    ScriptState* script_state) {
+  ExceptionState exception_state(script_state->GetIsolate(),
+                                 ExceptionState::kExecutionContext, nullptr,
+                                 nullptr);
+  ThrowUnimplemented(exception_state);
+  return nullptr;
+}
+
 void ReadableByteStreamController::ThrowUnimplemented(
     ExceptionState& exception_state) {
   exception_state.ThrowTypeError("unimplemented");

third_party/blink/renderer/core/streams/readable_byte_stream_controller.h

@@ -7,17 +7,20 @@
 
 #include "base/optional.h"
 #include "third_party/blink/renderer/bindings/core/v8/script_value.h"
+#include "third_party/blink/renderer/core/streams/readable_stream_controller.h"
 #include "third_party/blink/renderer/core/typed_arrays/array_buffer_view_helpers.h"
 #include "third_party/blink/renderer/platform/bindings/script_wrappable.h"
+#include "v8/include/v8.h"
 
 namespace blink {
 
-class ExceptionState;
-class ScriptState;
 class DOMArrayBufferView;
+class ExceptionState;
 class ReadableStreamBYOBRequest;
+class ScriptState;
+class StreamPromiseResolver;
 
-class ReadableByteStreamController : public ScriptWrappable {
+class ReadableByteStreamController : public ReadableStreamController {
   DEFINE_WRAPPERTYPEINFO();
 
  public:
@@ -39,6 +42,13 @@ class ReadableByteStreamController : public ScriptWrappable {
   void error(ScriptState*, ExceptionState&);
   void error(ScriptState*, ScriptValue e, ExceptionState&);
 
+  // https://streams.spec.whatwg.org/#rbs-controller-private-cancel
+  v8::Local<v8::Promise> CancelSteps(ScriptState*,
+                                     v8::Local<v8::Value> reason) override;
+
+  // https://streams.spec.whatwg.org/#rbs-controller-private-pull
+  StreamPromiseResolver* PullSteps(ScriptState*) override;
+
  private:
   static void ThrowUnimplemented(ExceptionState&);
 };

third_party/blink/renderer/core/streams/readable_stream_controller.h

+// Copyright 2020 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 THIRD_PARTY_BLINK_RENDERER_CORE_STREAMS_READABLE_STREAM_CONTROLLER_H_
+#define THIRD_PARTY_BLINK_RENDERER_CORE_STREAMS_READABLE_STREAM_CONTROLLER_H_
+
+#include "third_party/blink/renderer/platform/bindings/script_wrappable.h"
+#include "v8/include/v8.h"
+
+namespace blink {
+
+class ScriptState;
+class StreamPromiseResolver;
+
+class ReadableStreamController : public ScriptWrappable {
+ public:
+  // https://streams.spec.whatwg.org/#abstract-opdef-readablestreamcontroller-cancelsteps
+  virtual v8::Local<v8::Promise> CancelSteps(ScriptState*,
+                                             v8::Local<v8::Value> reason) = 0;
+
+  // https://streams.spec.whatwg.org/#abstract-opdef-readablestreamcontroller-pullsteps
+  virtual StreamPromiseResolver* PullSteps(ScriptState*) = 0;
+};
+
+}  // namespace blink
+
+#endif  // THIRD_PARTY_BLINK_RENDERER_CORE_STREAMS_READABLE_STREAM_CONTROLLER_H_

third_party/blink/renderer/core/streams/readable_stream_default_controller.h

@@ -6,7 +6,7 @@
 #define THIRD_PARTY_BLINK_RENDERER_CORE_STREAMS_READABLE_STREAM_DEFAULT_CONTROLLER_H_
 
 #include "base/optional.h"
-#include "third_party/blink/renderer/platform/bindings/script_wrappable.h"
+#include "third_party/blink/renderer/core/streams/readable_stream_controller.h"
 #include "v8/include/v8.h"
 
 namespace blink {
@@ -21,7 +21,7 @@ class StreamAlgorithm;
 class StreamPromiseResolver;
 class StreamStartAlgorithm;
 
-class ReadableStreamDefaultController : public ScriptWrappable {
+class ReadableStreamDefaultController : public ReadableStreamController {
   DEFINE_WRAPPERTYPEINFO();
 
  public:
@@ -72,15 +72,16 @@ class ReadableStreamDefaultController : public ScriptWrappable {
 
   void Trace(Visitor*) const override;
 
- private:
-  friend class ReadableStream;
-  friend class ReadableStreamDefaultReader;
-
   // https://streams.spec.whatwg.org/#rs-default-controller-private-cancel
-  v8::Local<v8::Promise> CancelSteps(ScriptState*, v8::Local<v8::Value> reason);
+  v8::Local<v8::Promise> CancelSteps(ScriptState*,
+                                     v8::Local<v8::Value> reason) override;
 
   // https://streams.spec.whatwg.org/#rs-default-controller-private-pull
-  StreamPromiseResolver* PullSteps(ScriptState*);
+  StreamPromiseResolver* PullSteps(ScriptState*) override;
+
+ private:
+  friend class ReadableStream;
+  friend class ReadableStreamDefaultReader;
 
   // https://streams.spec.whatwg.org/#readable-stream-default-controller-call-pull-if-needed
   static void CallPullIfNeeded(ScriptState*, ReadableStreamDefaultController*);