Introduce print backend mojom with Paper struct

Adding support for PrintBackend queries to happen out of the browser
process requires related data structures to be made available via a Mojo
interface.  These are moved into their own mojom file separate from the
common definition in printing/mojom since they are specific to a new
process being introduced and do not need to be encumbered by the
dependencies which exist for print.mojom.

Starting with the historically most prolific cause of browser crashes
from printing (GetPrinterSemanticCapsAndDefaults), work towards having
support definitions to enable that query to be moved out-of-process.

Start with a mojo definition for the
printing::PrinterSemanticCapsAndDefaults::Paper structure, which is
required for the larger query.

Bug: 809738
Change-Id: Id7d52f131f8587b9edc50c8e1c4f8b6718998965
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2387409Reviewed-by: Robert Sesek <rsesek@chromium.org>
Reviewed-by: Ken Rockot <rockot@google.com>
Reviewed-by: Daniel Hosseinian <dhoss@chromium.org>
Reviewed-by: Lei Zhang <thestig@chromium.org>
Commit-Queue: Alan Screen <awscreen@chromium.org>
Cr-Commit-Position: refs/heads/master@{#812424}

printing/BUILD.gn

@@ -325,6 +325,7 @@ static_library("test_support") {
 
 test("printing_unittests") {
   sources = [
+    "backend/mojom/print_backend_mojom_traits_unittest.cc",
     "metafile_skia_unittest.cc",
     "nup_parameters_unittest.cc",
     "page_number_unittest.cc",
@@ -340,8 +341,10 @@ test("printing_unittests") {
   configs += [ "//build/config/compiler:noshadowing" ]
   deps = [
     ":printing",
-    "//base/test:run_all_unittests",
     "//base/test:test_support",
+    "//mojo/core/test:run_all_unittests",
+    "//mojo/public/cpp/test_support:test_utils",
+    "//printing/backend/mojom",
     "//printing/common",
     "//printing/mojom",
     "//testing/gmock",

printing/DEPS

 include_rules = [
   "+cc/paint",
+  "+mojo/public",
   "+printing/printing_jni_headers",
   "+skia/ext",
   "+third_party/icu/source/common/unicode",

printing/backend/mojom/BUILD.gn

+# Copyright 2020 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.
+
+import("//mojo/public/tools/bindings/mojom.gni")
+
+mojom("mojom") {
+  sources = [ "print_backend.mojom" ]
+
+  deps = [ "//ui/gfx/geometry/mojom" ]
+
+  cpp_typemaps = [
+    {
+      types = [
+        {
+          mojom = "printing.mojom.Paper"
+          cpp = "::printing::PrinterSemanticCapsAndDefaults::Paper"
+        },
+      ]
+      traits_sources = [ "print_backend_mojom_traits.cc" ]
+      traits_headers = [ "print_backend_mojom_traits.h" ]
+    },
+  ]
+}

printing/backend/mojom/OWNERS

+per-file *.mojom=set noparent
+per-file *.mojom=file://ipc/SECURITY_OWNERS
+per-file *_mojom_traits*.*=set noparent
+per-file *_mojom_traits*.*=file://ipc/SECURITY_OWNERS

printing/backend/mojom/print_backend.mojom

+// Copyright 2020 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 printing.mojom;
+
+import "ui/gfx/geometry/mojom/geometry.mojom";
+
+// Paper used by printer semantic capabilities and defaults.
+struct Paper {
+  string display_name;
+  string vendor_id;
+  gfx.mojom.Size size_um;
+};
+

printing/backend/mojom/print_backend_mojom_traits.cc

+// Copyright 2020 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 "printing/backend/mojom/print_backend_mojom_traits.h"
+#include "ui/gfx/geometry/mojom/geometry.mojom-shared.h"
+#include "ui/gfx/geometry/mojom/geometry_mojom_traits.h"
+
+namespace mojo {
+
+// static
+bool StructTraits<printing::mojom::PaperDataView,
+                  printing::PrinterSemanticCapsAndDefaults::Paper>::
+    Read(printing::mojom::PaperDataView data,
+         printing::PrinterSemanticCapsAndDefaults::Paper* out) {
+  return data.ReadDisplayName(&out->display_name) &&
+         data.ReadVendorId(&out->vendor_id) && data.ReadSizeUm(&out->size_um);
+}
+
+}  // namespace mojo

printing/backend/mojom/print_backend_mojom_traits.h

+// Copyright 2020 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 PRINTING_BACKEND_MOJOM_PRINT_BACKEND_MOJOM_TRAITS_H_
+#define PRINTING_BACKEND_MOJOM_PRINT_BACKEND_MOJOM_TRAITS_H_
+
+#include <string>
+
+#include "printing/backend/mojom/print_backend.mojom-shared.h"
+#include "printing/backend/print_backend.h"
+#include "ui/gfx/geometry/size.h"
+
+namespace mojo {
+
+template <>
+struct StructTraits<printing::mojom::PaperDataView,
+                    printing::PrinterSemanticCapsAndDefaults::Paper> {
+  static const std::string& display_name(
+      const printing::PrinterSemanticCapsAndDefaults::Paper& p) {
+    return p.display_name;
+  }
+  static const std::string& vendor_id(
+      const printing::PrinterSemanticCapsAndDefaults::Paper& p) {
+    return p.vendor_id;
+  }
+  static const gfx::Size& size_um(
+      const printing::PrinterSemanticCapsAndDefaults::Paper& p) {
+    return p.size_um;
+  }
+
+  static bool Read(printing::mojom::PaperDataView data,
+                   printing::PrinterSemanticCapsAndDefaults::Paper* out);
+};
+
+}  // namespace mojo
+
+#endif  // PRINTING_BACKEND_MOJOM_PRINT_BACKEND_MOJOM_TRAITS_H_

printing/backend/mojom/print_backend_mojom_traits_unittest.cc

+// Copyright 2020 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/test_support/test_utils.h"
+#include "printing/backend/mojom/print_backend.mojom.h"
+#include "printing/backend/print_backend.h"
+#include "testing/gtest/include/gtest/gtest.h"
+#include "ui/gfx/geometry/size.h"
+
+namespace printing {
+
+namespace {
+
+const printing::PrinterSemanticCapsAndDefaults::Paper kPaperA3{
+    /*display_name=*/"A3", /*vendor_id=*/"67",
+    /*size_um=*/gfx::Size(7016, 9921)};
+const printing::PrinterSemanticCapsAndDefaults::Paper kPaperA4{
+    /*display_name=*/"A4", /*vendor_id=*/"12",
+    /*size_um=*/gfx::Size(4961, 7016)};
+const printing::PrinterSemanticCapsAndDefaults::Paper kPaperLetter{
+    /*display_name=*/"Letter", /*vendor_id=*/"45",
+    /*size_um=*/gfx::Size(5100, 6600)};
+const printing::PrinterSemanticCapsAndDefaults::Paper kPaperLedger{
+    /*display_name=*/"Ledger", /*vendor_id=*/"89",
+    /*size_um=*/gfx::Size(6600, 10200)};
+
+}  // namespace
+
+TEST(PrintBackendMojomTraitsTest, TestSerializeAndDeserializePaper) {
+  const printing::PrinterSemanticCapsAndDefaults::Papers kPapers{
+      kPaperA3, kPaperA4, kPaperLetter, kPaperLedger};
+
+  for (const auto& paper : kPapers) {
+    printing::PrinterSemanticCapsAndDefaults::Paper input = paper;
+    printing::PrinterSemanticCapsAndDefaults::Paper output;
+    EXPECT_TRUE(mojo::test::SerializeAndDeserialize<printing::mojom::Paper>(
+        &input, &output));
+    EXPECT_EQ(paper, output);
+  }
+}
+
+}  // namespace printing

printing/backend/print_backend.cc

@@ -37,6 +37,12 @@ AdvancedCapability::~AdvancedCapability() = default;
 
 #endif  // defined(OS_CHROMEOS)
 
+bool PrinterSemanticCapsAndDefaults::Paper::operator==(
+    const PrinterSemanticCapsAndDefaults::Paper& other) const {
+  return display_name == other.display_name && vendor_id == other.vendor_id &&
+         size_um == other.size_um;
+}
+
 PrinterSemanticCapsAndDefaults::PrinterSemanticCapsAndDefaults() = default;
 
 PrinterSemanticCapsAndDefaults::PrinterSemanticCapsAndDefaults(

printing/backend/print_backend.h

@@ -105,10 +105,12 @@ struct PRINTING_EXPORT PrinterSemanticCapsAndDefaults {
   mojom::ColorModel color_model = mojom::ColorModel::kUnknownColorModel;
   mojom::ColorModel bw_model = mojom::ColorModel::kUnknownColorModel;
 
-  struct Paper {
+  struct PRINTING_EXPORT Paper {
     std::string display_name;
     std::string vendor_id;
     gfx::Size size_um;
+
+    bool operator==(const Paper& other) const;
   };
   using Papers = std::vector<Paper>;
   Papers papers;