Adds Mojo IDL.

third_party/WebKit/Source/core/mojo/MojoHandle.cpp

Index: third_party/WebKit/Source/core/mojo/MojoHandle.cpp
diff --git a/third_party/WebKit/Source/core/mojo/MojoHandle.cpp b/third_party/WebKit/Source/core/mojo/MojoHandle.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..f3abddca293d751665bafc603282bfafb6a58fa3
--- /dev/null
+++ b/third_party/WebKit/Source/core/mojo/MojoHandle.cpp
@@ -0,0 +1,92 @@
+// Copyright 2016 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.
+
+#include "core/mojo/MojoHandle.h"
+
+#include "bindings/core/v8/ArrayBufferOrArrayBufferView.h"
+#include "bindings/core/v8/ScriptState.h"
+#include "core/dom/DOMArrayBuffer.h"
+#include "core/dom/DOMArrayBufferView.h"
+#include "core/mojo/MojoReadMessageOptions.h"
+#include "core/mojo/MojoReadMessageResult.h"
+#include "core/mojo/MojoWatcher.h"
+#include "core/mojo/MojoWriteMessageOptions.h"
+
+// Mojo messages typically do not contain many handles. In fact most
+// messages do not contain any handle. An inline capacity of 4 should avoid
+// heap allocation in vast majority of cases.
+static const size_t kHandleVectorInlineCapacity = 4;
+
+namespace blink {
+
+MojoHandle* MojoHandle::create(mojo::ScopedHandle handle) {
+  return new MojoHandle(std::move(handle));
+}
+
+MojoHandle::MojoHandle(mojo::ScopedHandle handle)
+    : m_handle(std::move(handle)) {}
+
+MojoResult MojoHandle::close() {
+  return mojo::CloseRaw(m_handle.release());

[jbroman, 2017/01/10 20:46:30]

Can this fail (in a case where the result will be useful on the JS side)?

Most places seem to DCHECK that this is MOJO_RESULT_OK. In that case, maybe this
would work:

void MojoHandle::close() {
  m_handle.reset();
}

Otherwise, maybe a comment explaining this would be helpful.

[alokp, 2017/01/11 21:53:01]

I followed the cpp API - mojo::Handle::Close - and got rid of the return value.

+}
+
+MojoWatcher* MojoHandle::watch(ScriptState* scriptState,
+                               MojoHandleSignals signals,
+                               MojoWatchCallback* callback) {
+  return MojoWatcher::create(m_handle.get(), signals, callback,
+                             scriptState->getExecutionContext());
+}
+
+MojoResult MojoHandle::writeMessage(const MojoWriteMessageOptions& options) {
+  // MojoWriteMessage takes ownership of the handles, so release them here.
+  Vector<::MojoHandle, kHandleVectorInlineCapacity> rawHandles(
+      options.handles().size());
+  std::transform(
+      options.handles().begin(), options.handles().end(), rawHandles.begin(),
+      [](MojoHandle* handle) { return handle->m_handle.release().value(); });
+
+  const void* bytes = nullptr;
+  uint32_t numBytes = 0;
+  if (options.buffer().isArrayBuffer()) {
+    DOMArrayBuffer* array = options.buffer().getAsArrayBuffer();
+    bytes = array->data();
+    numBytes = array->byteLength();
+  } else {
+    DOMArrayBufferView* view = options.buffer().getAsArrayBufferView();
+    bytes = view->baseAddress();
+    numBytes = view->byteLength();
+  }
+
+  return MojoWriteMessage(m_handle->value(), bytes, numBytes, rawHandles.data(),
+                          rawHandles.size(), options.flags());
+}
+
+void MojoHandle::readMessage(const MojoReadMessageOptions& options,
+                             MojoReadMessageResult& resultDict) {
+  uint32_t numBytes = 0, numHandles = 0;
+  MojoResult result = MojoReadMessage(m_handle->value(), nullptr, &numBytes,
+                                      nullptr, &numHandles, options.flags());
+  if (result != MOJO_RESULT_RESOURCE_EXHAUSTED) {
+    resultDict.setResult(result);
+    return;
+  }
+
+  DCHECK_GT(numBytes, 0u);
+  DOMArrayBuffer* buffer = DOMArrayBuffer::createUninitialized(numBytes, 1);
+  Vector<::MojoHandle, kHandleVectorInlineCapacity> rawHandles(numHandles);
+  result = MojoReadMessage(m_handle->value(), buffer->data(), &numBytes,
+                           rawHandles.data(), &numHandles, options.flags());
+
+  HeapVector<Member<MojoHandle>> handles(numHandles);
+  for (size_t i = 0; i < numHandles; ++i) {
+    handles[i] =
+        MojoHandle::create(mojo::MakeScopedHandle(mojo::Handle(rawHandles[i])));
+  }
+
+  resultDict.setResult(result);
+  resultDict.setBuffer(buffer);
+  resultDict.setHandles(handles);
+}
+
+}  // namespace blink