Implementation of ReadableStream pipeTo and pipeThrough

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

Index: third_party/WebKit/Source/core/streams/WritableStream.js
diff --git a/third_party/WebKit/Source/core/streams/WritableStream.js b/third_party/WebKit/Source/core/streams/WritableStream.js
index e987cedd7f85b4496a9d3cff686013165fcf546d..d7cc5243511bed8f8a989b231edbd68b26e02474 100644
--- a/third_party/WebKit/Source/core/streams/WritableStream.js
+++ b/third_party/WebKit/Source/core/streams/WritableStream.js
@@ -364,6 +364,26 @@
     }
   }
 
+  // Functions to expose internals for ReadableStream.pipeTo. These are not
+  // part of the standard.
+  function IsWritableStreamErrored(stream) {
+    TEMP_ASSERT(IsWritableStream(stream),
+                '! IsWritableStream(stream) is true.');
+    return stream[_state] === ERRORED;
+  }
+
+  function IsWritableStreamClosingOrClosed(stream) {
+    TEMP_ASSERT(IsWritableStream(stream),
+                '! IsWritableStream(stream) is true.');
+    return stream[_state] === CLOSING || stream[_state] === CLOSED;
+  }
+
+  function WritableStreamStoredError(stream) {
+    TEMP_ASSERT(IsWritableStream(stream),
+                '! IsWritableStream(stream) is true.');
+    return stream[_storedError];
+  }
+
   class WritableStreamDefaultWriter {
     constructor(stream) {
       if (!IsWritableStream(stream)) {
@@ -504,6 +524,20 @@
     return stream[_pendingCloseRequest];
   }
 
+  function WritableStreamDefaultWriterCloseWithErrorPropagation(writer) {
+    const stream = writer[_ownerWritableStream];
+    TEMP_ASSERT(stream !== undefined, 'stream is not undefined.');
+    const state = stream[_state];
+    if (state === CLOSING || state === CLOSED) {
+      return Promise_resolve(undefined);
+    }
+    if (state === ERRORED) {
+      return Promise_reject(stream[_storedError]);
+    }
+    TEMP_ASSERT(state === WRITABLE, 'state is "writable".');
+    return WritableStreamDefaultWriterClose(writer);
+  }
+
   function WritableStreamDefaultWriterGetDesiredSize(writer) {
     const stream = writer[_ownerWritableStream];
     const state = stream[_state];
@@ -563,6 +597,20 @@
     return promise;
   }
 
+  // Functions to expose internals for ReadableStream.pipeTo. These do not
+  // appear in the standard.
+  function WritableStreamDefaultWriterClosedPromise(writer) {
+    TEMP_ASSERT(IsWritableStreamDefaultWriter(writer),
+                'writer is a WritableStreamDefaultWriter');
+    return writer[_closedPromise];
+  }
+
+  function WritableStreamDefaultWriterReadyPromise(writer) {
+    TEMP_ASSERT(IsWritableStreamDefaultWriter(writer),
+                'writer is a WritableStreamDefaultWriter');
+    return writer[_readyPromise];
+  }
+
   class WritableStreamDefaultController {
     constructor(stream, underlyingSink, size, highWaterMark) {
       if (!IsWritableStream(stream)) {
@@ -934,4 +982,25 @@
   });
 
   // TODO(ricea): Exports to Blink
+
+  // Exports for ReadableStream
+  binding.AcquireWritableStreamDefaultWriter =
+      AcquireWritableStreamDefaultWriter;
+  binding.IsWritableStream = IsWritableStream;
+  binding.IsWritableStreamClosingOrClosed = IsWritableStreamClosingOrClosed;
+  binding.IsWritableStreamErrored = IsWritableStreamErrored;
+  binding.IsWritableStreamLocked = IsWritableStreamLocked;
+  binding.WritableStreamAbort = WritableStreamAbort;
+  binding.WritableStreamDefaultWriterCloseWithErrorPropagation =
+      WritableStreamDefaultWriterCloseWithErrorPropagation;
+  binding.WritableStreamDefaultWriterClosedPromise =
+      WritableStreamDefaultWriterClosedPromise;
+  binding.WritableStreamDefaultWriterGetDesiredSize =
+      WritableStreamDefaultWriterGetDesiredSize;
+  binding.WritableStreamDefaultWriterReadyPromise =
+      WritableStreamDefaultWriterReadyPromise;
+  binding.WritableStreamDefaultWriterRelease =
+      WritableStreamDefaultWriterRelease;
+  binding.WritableStreamDefaultWriterWrite = WritableStreamDefaultWriterWrite;
+  binding.WritableStreamStoredError = WritableStreamStoredError;
 });