Change FilePath to use EnableIf instead of native typemapping.

Bug: 676224
Change-Id: I101d138ac8ca72815cc6aa0a1b5ad4218b3c3001
Reviewed-on: https://chromium-review.googlesource.com/1065753
Reviewed-by: Ken Rockot <rockot@chromium.org>
Reviewed-by: Daniel Cheng <dcheng@chromium.org>
Commit-Queue: Sam McNally <sammc@chromium.org>
Cr-Commit-Position: refs/heads/master@{#560839}

diff --git a/chrome/services/util_win/public/mojom/shell_util_win.typemap b/chrome/services/util_win/public/mojom/shell_util_win.typemap
index 7e05c23..dcbf2a0 100644
--- a/chrome/services/util_win/public/mojom/shell_util_win.typemap
+++ b/chrome/services/util_win/public/mojom/shell_util_win.typemap

@@ -5,6 +5,7 @@
 mojom = "//chrome/services/util_win/public/mojom/shell_util_win.mojom"
 
 public_headers = [ "//base/strings/string16.h" ]
+traits_headers = [ "//ipc/ipc_message_utils.h" ]
 
 deps = [
   "//base",

diff --git a/mojo/public/cpp/base/BUILD.gn b/mojo/public/cpp/base/BUILD.gn
index 78a615a..e97ccda 100644
--- a/mojo/public/cpp/base/BUILD.gn
+++ b/mojo/public/cpp/base/BUILD.gn

@@ -30,6 +30,8 @@
   sources = [
     "big_buffer_mojom_traits.cc",
     "big_buffer_mojom_traits.h",
+    "file_path_mojom_traits.cc",
+    "file_path_mojom_traits.h",
     "shared_memory_mojom_traits.cc",
     "shared_memory_mojom_traits.h",
     "values_mojom_traits.cc",

diff --git a/mojo/public/cpp/base/file_path.typemap b/mojo/public/cpp/base/file_path.typemap
index 682200f..aa30b2d8 100644
--- a/mojo/public/cpp/base/file_path.typemap
+++ b/mojo/public/cpp/base/file_path.typemap

@@ -4,9 +4,9 @@
 
 mojom = "//mojo/public/mojom/base/file_path.mojom"
 public_headers = [ "//base/files/file_path.h" ]
-traits_headers = [ "//ipc/ipc_message_utils.h" ]
+traits_headers = [ "//mojo/public/cpp/base/file_path_mojom_traits.h" ]
 public_deps = [
-  "//ipc",
+  "//mojo/public/cpp/base:shared_typemap_traits",
 ]
 
 type_mappings = [ "mojo_base.mojom.FilePath=base::FilePath" ]

diff --git a/mojo/public/cpp/base/file_path_mojom_traits.cc b/mojo/public/cpp/base/file_path_mojom_traits.cc
new file mode 100644
index 0000000..f7af33d
--- /dev/null
+++ b/mojo/public/cpp/base/file_path_mojom_traits.cc

@@ -0,0 +1,28 @@
+// 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/file_path_mojom_traits.h"
+
+namespace mojo {
+
+// static
+bool StructTraits<mojo_base::mojom::FilePathDataView, base::FilePath>::Read(
+    mojo_base::mojom::FilePathDataView data,
+    base::FilePath* out) {
+  base::FilePath::StringPieceType path_view;
+#if defined(OS_WIN)
+  ArrayDataView<uint16_t> view;
+  data.GetPathDataView(&view);
+  path_view.set(reinterpret_cast<const base::char16*>(view.data()),
+                view.size());
+#else
+  if (!data.ReadPath(&path_view)) {
+    return false;
+  }
+#endif
+  *out = base::FilePath(path_view);
+  return true;
+}
+
+}  // namespace mojo

diff --git a/mojo/public/cpp/base/file_path_mojom_traits.h b/mojo/public/cpp/base/file_path_mojom_traits.h
new file mode 100644
index 0000000..f974f1c2
--- /dev/null
+++ b/mojo/public/cpp/base/file_path_mojom_traits.h

@@ -0,0 +1,38 @@
+// 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_FILE_PATH_MOJOM_TRAITS_H_
+#define MOJO_PUBLIC_CPP_BASE_FILE_PATH_MOJOM_TRAITS_H_
+
+#include "base/component_export.h"
+#include "base/containers/span.h"
+#include "base/files/file_path.h"
+#include "build/build_config.h"
+#include "mojo/public/cpp/bindings/struct_traits.h"
+#include "mojo/public/mojom/base/file_path.mojom-shared.h"
+
+namespace mojo {
+
+template <>
+struct COMPONENT_EXPORT(MOJO_BASE_SHARED_TRAITS)
+    StructTraits<mojo_base::mojom::FilePathDataView, base::FilePath> {
+#if defined(OS_WIN)
+  static base::span<const uint16_t> path(const base::FilePath& path) {
+    return base::make_span(
+        reinterpret_cast<const uint16_t*>(path.value().data()),
+        path.value().size());
+  }
+#else
+  static const base::FilePath::StringType& path(const base::FilePath& path) {
+    return path.value();
+  }
+#endif
+
+  static bool Read(mojo_base::mojom::FilePathDataView data,
+                   base::FilePath* out);
+};
+
+}  // namespace mojo
+
+#endif  // MOJO_PUBLIC_CPP_BASE_FILE_PATH_MOJOM_TRAITS_H_

diff --git a/mojo/public/cpp/base/file_path_unittest.cc b/mojo/public/cpp/base/file_path_unittest.cc
index 9c53bff..a5b027a9 100644
--- a/mojo/public/cpp/base/file_path_unittest.cc
+++ b/mojo/public/cpp/base/file_path_unittest.cc

@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-#include "ipc/ipc_message_utils.h"
+#include "mojo/public/cpp/base/file_path_mojom_traits.h"
 #include "mojo/public/cpp/test_support/test_utils.h"
 #include "mojo/public/mojom/base/file_path.mojom.h"
 #include "testing/gtest/include/gtest/gtest.h"

diff --git a/mojo/public/mojom/base/BUILD.gn b/mojo/public/mojom/base/BUILD.gn
index acbc814..807d4b9 100644
--- a/mojo/public/mojom/base/BUILD.gn
+++ b/mojo/public/mojom/base/BUILD.gn

@@ -27,9 +27,11 @@
   if (is_win) {
     sources += [ "logfont_win.mojom" ]
   }
-
-  if (is_posix && !is_android && !is_fuchsia && !is_mac) {
-    enabled_features = [ "shared_memory_region_uses_fd_pair" ]
+  enabled_features = []
+  if (is_win) {
+    enabled_features += [ "file_path_is_string16" ]
+  } else {
+    enabled_features += [ "file_path_is_string" ]
   }
 
   output_prefix = "mojo_base_mojom"

diff --git a/mojo/public/mojom/base/file_path.mojom b/mojo/public/mojom/base/file_path.mojom
index cbe0bbe..674d8cd 100644
--- a/mojo/public/mojom/base/file_path.mojom
+++ b/mojo/public/mojom/base/file_path.mojom

@@ -4,5 +4,15 @@
 
 module mojo_base.mojom;
 
-[Native]
-struct FilePath;
+struct FilePath {
+  [EnableIf=file_path_is_string]
+  string path;
+
+  // This duplicates the contents of mojo_base.mojom.String16. String16 isn't
+  // used here due to typemapping dependency problems. base::FilePath is
+  // used for the typemap for both variants, but base::string16 and WTF::String
+  // are used for mojo_base.mojom.String16 typemapping. This mismatch causes
+  // problems with dependencies.
+  [EnableIf=file_path_is_string16]
+  array<uint16> path;
+};

diff --git a/ui/display/mojo/display_snapshot_struct_traits.cc b/ui/display/mojo/display_snapshot_struct_traits.cc
index 165c378e6..2132e86 100644
--- a/ui/display/mojo/display_snapshot_struct_traits.cc
+++ b/ui/display/mojo/display_snapshot_struct_traits.cc

@@ -4,6 +4,7 @@
 
 #include "ui/display/mojo/display_snapshot_struct_traits.h"
 
+#include "mojo/public/cpp/base/file_path_mojom_traits.h"
 #include "ui/display/types/display_constants.h"
 #include "ui/gfx/color_space.h"
 #include "ui/gfx/geometry/size.h"

diff --git a/ui/display/mojo/display_struct_traits_unittest.cc b/ui/display/mojo/display_struct_traits_unittest.cc
index 8d956238..f20bb0545 100644
--- a/ui/display/mojo/display_struct_traits_unittest.cc
+++ b/ui/display/mojo/display_struct_traits_unittest.cc

@@ -8,6 +8,7 @@
 #include <vector>
 
 #include "base/macros.h"
+#include "mojo/public/cpp/base/file_path_mojom_traits.h"
 #include "testing/gtest/include/gtest/gtest.h"
 #include "ui/display/display.h"
 #include "ui/display/display_layout.h"