Add mojo support for base::RefCountedMemory.

RefCountedMemory is an arbitrary wrapper around memory. It is used
extensively in code which passes encoded PNG files around, such as the
history system and the screenshotting code.

Bug: 706246
Change-Id: I9788aaba9dcfe38bd05418c4cc3a9e2737a5985c
Reviewed-on: https://chromium-review.googlesource.com/917198Reviewed-by: Tom Sepez <tsepez@chromium.org>
Reviewed-by: Ken Rockot <rockot@chromium.org>
Commit-Queue: Elliot Glaysher <erg@chromium.org>
Cr-Commit-Position: refs/heads/master@{#536914}

mojo/public/cpp/base/BUILD.gn

@@ -46,6 +46,7 @@ source_set("tests") {
   sources = [
     "big_buffer_unittest.cc",
     "big_string_unittest.cc",
+    "ref_counted_memory_unittest.cc",
     "string16_unittest.cc",
   ]
 

mojo/public/cpp/base/ref_counted_memory.typemap

+# Copyright 2018 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.
+
+mojom = "//mojo/public/mojom/base/ref_counted_memory.mojom"
+public_headers = [ "//base/memory/ref_counted_memory.h" ]
+traits_headers = [ "//mojo/public/cpp/base/ref_counted_memory_mojom_traits.h" ]
+sources = [
+  "//mojo/public/cpp/base/ref_counted_memory_mojom_traits.cc",
+  "//mojo/public/cpp/base/ref_counted_memory_mojom_traits.h",
+]
+public_deps = [
+  "//base",
+  "//mojo/public/cpp/base",
+  "//mojo/public/cpp/base:shared_typemap_traits",
+]
+type_mappings = [ "mojo.common.mojom.RefCountedMemory=scoped_refptr<base::RefCountedMemory>[copyable_pass_by_value,nullable_is_same_type]" ]

mojo/public/cpp/base/ref_counted_memory_mojom_traits.cc

+// Copyright 2018 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 "mojo/public/cpp/base/ref_counted_memory_mojom_traits.h"
+
+#include "mojo/public/cpp/base/big_buffer_mojom_traits.h"
+
+namespace mojo {
+
+// static
+mojo_base::BigBuffer StructTraits<mojo_base::mojom::RefCountedMemoryDataView,
+                                  scoped_refptr<base::RefCountedMemory>>::
+    data(const scoped_refptr<base::RefCountedMemory>& in) {
+  return mojo_base::BigBuffer(base::make_span(in->front(), in->size()));
+}
+
+// static
+bool StructTraits<mojo_base::mojom::RefCountedMemoryDataView,
+                  scoped_refptr<base::RefCountedMemory>>::
+    IsNull(const scoped_refptr<base::RefCountedMemory>& input) {
+  return !input.get();
+}
+
+// static
+void StructTraits<mojo_base::mojom::RefCountedMemoryDataView,
+                  scoped_refptr<base::RefCountedMemory>>::
+    SetToNull(scoped_refptr<base::RefCountedMemory>* out) {
+  *out = scoped_refptr<base::RefCountedMemory>();
+}
+
+// static
+bool StructTraits<mojo_base::mojom::RefCountedMemoryDataView,
+                  scoped_refptr<base::RefCountedMemory>>::
+    Read(mojo_base::mojom::RefCountedMemoryDataView data,
+         scoped_refptr<base::RefCountedMemory>* out) {
+  mojo_base::BigBuffer buffer;
+  if (!data.ReadData(&buffer))
+    return false;
+
+  *out =
+      base::MakeRefCounted<base::RefCountedBytes>(buffer.data(), buffer.size());
+  return true;
+}
+
+}  // namespace mojo

mojo/public/cpp/base/ref_counted_memory_mojom_traits.h

+// Copyright 2018 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.
+
+#ifndef MOJO_PUBLIC_CPP_BASE_REF_COUNTED_MEMORY_MOJOM_TRAITS_H_
+#define MOJO_PUBLIC_CPP_BASE_REF_COUNTED_MEMORY_MOJOM_TRAITS_H_
+
+#include <string>
+
+#include "base/component_export.h"
+#include "base/memory/ref_counted_memory.h"
+#include "mojo/public/cpp/base/big_buffer.h"
+#include "mojo/public/cpp/bindings/struct_traits.h"
+#include "mojo/public/mojom/base/ref_counted_memory.mojom-shared.h"
+
+namespace mojo {
+
+template <>
+struct COMPONENT_EXPORT(MOJO_BASE_MOJOM)
+    StructTraits<mojo_base::mojom::RefCountedMemoryDataView,
+                 scoped_refptr<base::RefCountedMemory>> {
+  static mojo_base::BigBuffer data(
+      const scoped_refptr<base::RefCountedMemory>& in);
+
+  static bool IsNull(const scoped_refptr<base::RefCountedMemory>& input);
+  static void SetToNull(scoped_refptr<base::RefCountedMemory>* out);
+
+  static bool Read(mojo_base::mojom::RefCountedMemoryDataView data,
+                   scoped_refptr<base::RefCountedMemory>* out);
+};
+
+}  // namespace mojo
+
+#endif  // MOJO_PUBLIC_CPP_BASE_REF_COUNTED_MEMORY_MOJOM_TRAITS_H_

mojo/public/cpp/base/ref_counted_memory_unittest.cc

+// Copyright 2018 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 "mojo/public/cpp/base/big_buffer_mojom_traits.h"
+#include "mojo/public/cpp/base/ref_counted_memory_mojom_traits.h"
+#include "mojo/public/cpp/test_support/test_utils.h"
+#include "mojo/public/mojom/base/ref_counted_memory.mojom.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace mojo_base {
+
+TEST(RefCountedMemoryTest, Data) {
+  uint8_t data[] = {'a', 'b', 'c', 'd', 'e'};
+
+  scoped_refptr<base::RefCountedMemory> in =
+      new base::RefCountedStaticMemory(&data, arraysize(data));
+
+  scoped_refptr<base::RefCountedMemory> out;
+  ASSERT_TRUE(
+      mojo::test::SerializeAndDeserialize<mojom::RefCountedMemory>(&in, &out));
+  ASSERT_EQ(out->size(), in->size());
+  for (size_t i = 0; i < out->size(); ++i)
+    EXPECT_EQ(in->front()[i], out->front()[i]);
+}
+
+TEST(RefCountedMemoryTest, Null) {
+  // Stuff real data in out to ensure it gets overwritten with a null.
+  uint8_t data[] = {'a', 'b', 'c', 'd', 'e'};
+  scoped_refptr<base::RefCountedMemory> out =
+      new base::RefCountedStaticMemory(&data, arraysize(data));
+
+  scoped_refptr<base::RefCountedMemory> in;
+  ASSERT_TRUE(
+      mojo::test::SerializeAndDeserialize<mojom::RefCountedMemory>(&in, &out));
+
+  ASSERT_FALSE(out.get());
+}
+
+}  // namespace mojo_base

mojo/public/cpp/base/typemaps.gni

@@ -5,5 +5,6 @@
 typemaps = [
   "//mojo/public/cpp/base/big_buffer.typemap",
   "//mojo/public/cpp/base/big_string.typemap",
+  "//mojo/public/cpp/base/ref_counted_memory.typemap",
   "//mojo/public/cpp/base/string16.typemap",
 ]

mojo/public/mojom/base/BUILD.gn

@@ -8,6 +8,7 @@ mojom_component("base") {
   sources = [
     "big_buffer.mojom",
     "big_string.mojom",
+    "ref_counted_memory.mojom",
     "string16.mojom",
   ]
 

mojo/public/mojom/base/ref_counted_memory.mojom

+// Copyright 2018 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.
+
+module mojo_base.mojom;
+
+import "mojo/public/mojom/base/big_buffer.mojom";
+
+// Chrome internally uses base::RefCountedMemory to pass data around. These
+// data segments can be fairly large, to the point where we don't want them
+// to be stuffed raw through the mojo ipc layer.
+struct RefCountedMemory {
+  mojo_base.mojom.BigBuffer data;
+};