[Streams] UnderlyingSourceBase should be kept alive only when locked

third_party/WebKit/Source/core/streams/ReadableStream.js

Index: third_party/WebKit/Source/core/streams/ReadableStream.js
diff --git a/third_party/WebKit/Source/core/streams/ReadableStream.js b/third_party/WebKit/Source/core/streams/ReadableStream.js
index 414c92343120fd65d3d7f87f4c38c6ffede89c77..46eef5435553303d0e47641cef816609637f1980 100644
--- a/third_party/WebKit/Source/core/streams/ReadableStream.js
+++ b/third_party/WebKit/Source/core/streams/ReadableStream.js
@@ -276,6 +276,15 @@
         throw new TypeError(errReaderConstructorStreamAlreadyLocked);
       }
 
+      // TODO(yhirano): Remove this when we don't need hasPendingActivity in
+      // blink::UnderlyingSourceBase.
+      if (stream[readableStreamController] === null) {
+        // The stream is created with an external controller (i.e. made in
+        // Blink).
+        const underlyingSource = stream[readableStreamUnderlyingSource];
+        callFunction(underlyingSource.notifyLockAcquired, underlyingSource);
+      }
+
       this[readableStreamReaderOwnerReadableStream] = stream;
       stream[readableStreamReader] = this;
 
@@ -342,6 +351,15 @@
         throw new TypeError(errReleaseReaderWithPendingRead);
       }
 
+      // TODO(yhirano): Remove this when we don't need hasPendingActivity in
+      // blink::UnderlyingSourceBase.
+      if (stream[readableStreamController] === null) {
+        // The stream is created with an external controller (i.e. made in
+        // Blink).
+        const underlyingSource = stream[readableStreamUnderlyingSource];
+        callFunction(underlyingSource.notifyLockReleased, underlyingSource);
+      }
+
       if (stream[readableStreamState] === STATE_READABLE) {
         v8.rejectPromise(this[readableStreamReaderClosedPromise],
             new TypeError(errReleasedReaderClosedPromise));