Add PDF compositor service

components/printing/service/public/cpp/pdf_compositor_client.cc

+// Copyright 2017 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 "components/printing/service/public/cpp/pdf_compositor_client.h"
+
+#include <utility>
+
+#include "mojo/public/cpp/system/platform_handle.h"
+
+namespace printing {
+
+namespace {
+
+// Helper callback which owns an PdfCompositorPtr until invoked. This keeps the
+// PdfCompositor pipe open just long enough to dispatch a reply, at which point
+// the reply is forwarded to the wrapped |callback|.
+void OnCompositePdf(
+    printing::mojom::PdfCompositorPtr compositor,
+    const printing::mojom::PdfCompositor::CompositePdfCallback& callback,
+    scoped_refptr<base::SequencedTaskRunner> task_runner,
+    mojo::ScopedSharedBufferHandle pdf_handle) {
+  task_runner->PostTask(FROM_HERE,
+                        base::Bind(callback, base::Passed(&pdf_handle)));
+}
+
+}  // namespace
+
+PdfCompositorClient::PdfCompositorClient() : compositor_(nullptr) {}
+
+PdfCompositorClient::~PdfCompositorClient() {}
+
+void PdfCompositorClient::Connect(service_manager::Connector* connector) {
+  DCHECK(!compositor_.is_bound());
+  connector->BindInterface(mojom::kServiceName, &compositor_);
+}
+
+void PdfCompositorClient::Composite(
+    service_manager::Connector* connector,
+    base::SharedMemoryHandle handle,
+    uint32_t data_size,

[dcheng, 2017/05/10 07:36:48]

Any particular reason for uint32_t instead of size_t?

[Wei Li, 2017/05/11 16:53:02]

Done.

+    const mojom::PdfCompositor::CompositePdfCallback& callback,
+    scoped_refptr<base::SequencedTaskRunner> callback_task_runner) {
+  DCHECK(data_size);
+
+  if (!compositor_.get())

[dcheng, 2017/05/10 07:36:48]

Nit: no .get()

[Wei Li, 2017/05/11 16:53:02]

Done.

+    Connect(connector);
+
+  mojo::ScopedSharedBufferHandle buffer_handle =
+      mojo::WrapSharedMemoryHandle(handle, data_size, true);
+
+  compositor_.get()->CompositePdf(
+      std::move(buffer_handle),
+      base::Bind(&OnCompositePdf, base::Passed(&compositor_), callback,
+                 callback_task_runner));

[dcheng, 2017/05/10 07:36:48]

Optional: perhaps use base::Passed() with callback_task_runner, since this is
being passed by value?

[Wei Li, 2017/05/11 16:53:02]

Done.

+}
+
+}  // namespace printing