Add PDF compositor service

components/printing/service/pdf_compositor_impl.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/pdf_compositor_impl.h"
+
+#include <utility>
+#include <vector>
+
+#include "base/logging.h"
+#include "base/memory/shared_memory.h"
+#include "base/memory/shared_memory_handle.h"
+#include "mojo/public/cpp/system/platform_handle.h"
+#include "printing/common/pdf_metafile_utils.h"
+#include "third_party/skia/include/core/SkCanvas.h"
+#include "third_party/skia/include/core/SkDocument.h"
+#include "third_party/skia/src/utils/SkMultiPictureDocument.h"
+
+namespace printing {
+
+PdfCompositorImpl::PdfCompositorImpl(
+    const std::string& creator,
+    std::unique_ptr<service_manager::ServiceContextRef> service_ref)
+    : service_ref_(std::move(service_ref)), creator_(creator) {}
+
+PdfCompositorImpl::~PdfCompositorImpl() = default;
+
+void PdfCompositorImpl::CompositePdf(
+    mojo::ScopedSharedBufferHandle sk_handle,
+    mojom::PdfCompositor::CompositePdfCallback callback) {
+  DCHECK(sk_handle.is_valid());
+
+  base::SharedMemoryHandle memory_handle;
+  size_t memory_size = 0;
+  bool read_only_flag = false;
+
+  const MojoResult result = mojo::UnwrapSharedMemoryHandle(
+      std::move(sk_handle), &memory_handle, &memory_size, &read_only_flag);
+  DCHECK_EQ(MOJO_RESULT_OK, result);
+  DCHECK_GT(memory_size, 0u);
+
+  std::unique_ptr<base::SharedMemory> shm =

[dcheng, 2017/05/22 09:40:48]

FWIW, it's OK to use 'auto' as the typename in this case

+      base::MakeUnique<base::SharedMemory>(memory_handle, true);
+  if (!shm->Map(memory_size)) {
+    DLOG(ERROR) << "CompositePdf: Shared memory map failed.";
+    std::move(callback).Run(mojo::ScopedSharedBufferHandle());
+    return;
+  }
+
+  SkMemoryStream stream(shm->memory(), memory_size);
+  int page_count = SkMultiPictureDocumentReadPageCount(&stream);
+  if (!page_count) {
+    DLOG(ERROR) << "CompositePdf: No page is read.";
+    std::move(callback).Run(mojo::ScopedSharedBufferHandle());
+    return;
+  }
+
+  std::vector<SkDocumentPage> pages(page_count);
+  if (!SkMultiPictureDocumentRead(&stream, pages.data(), page_count)) {
+    DLOG(ERROR) << "CompositePdf: Page reading failed.";
+    std::move(callback).Run(mojo::ScopedSharedBufferHandle());
+    return;
+  }
+
+  SkDynamicMemoryWStream wstream;
+  sk_sp<SkDocument> doc = MakePdfDocument(creator_, &wstream);
+
+  for (const auto& page : pages) {
+    SkCanvas* canvas = doc->beginPage(page.fSize.width(), page.fSize.height());
+    canvas->drawPicture(page.fPicture);
+    doc->endPage();
+  }
+  doc->close();
+
+  mojo::ScopedSharedBufferHandle buffer =
+      mojo::SharedBufferHandle::Create(wstream.bytesWritten());
+  DCHECK(buffer.is_valid());
+
+  mojo::ScopedSharedBufferMapping mapping = buffer->Map(wstream.bytesWritten());
+  DCHECK(mapping);
+  wstream.copyToAndReset(mapping.get());
+
+  std::move(callback).Run(std::move(buffer));
+}
+
+}  // namespace printing