[mojo] Fixed mojo.common.mojom.Value builds inside Blink platform.

This patch moves values_struct_traits into a separate target to be shared by the
chromium and blink variant, and adds values.typemap to blink's typemap config.

BUG=740288

Change-Id: Iae1bf24dd90ca16af6f7b3e0d3e83d255ae41b16
Reviewed-on: https://chromium-review.googlesource.com/565337
Commit-Queue: lpy <lpy@chromium.org>
Reviewed-by: Mike West <mkwst@chromium.org>
Reviewed-by: Yuzhu Shen <yzshen@chromium.org>
Cr-Commit-Position: refs/heads/master@{#485852}

mojo/common/BUILD.gn

@@ -96,3 +96,15 @@ source_set("struct_traits") {
     "//base:i18n",
   ]
 }
+
+source_set("values_struct_traits") {
+  sources = [
+    "values_struct_traits.cc",
+    "values_struct_traits.h",
+  ]
+  public_deps = [
+    ":common_custom_types_shared_cpp_sources",
+    "//base",
+    "//mojo/public/cpp/bindings:bindings",
+  ]
+}

mojo/common/values.typemap

@@ -8,13 +8,14 @@ traits_headers = [
   "//ipc/ipc_message_utils.h",
   "//mojo/common/values_struct_traits.h",
 ]
+
 public_deps = [
   "//base",
   "//ipc",
 ]
-sources = [
-  "values_struct_traits.cc",
-  "values_struct_traits.h",
+
+deps = [
+  "//mojo/common:values_struct_traits",
 ]
 
 type_mappings = [

mojo/common/values_struct_traits.h

@@ -6,7 +6,7 @@
 #define MOJO_COMMON_VALUES_STRUCT_TRAITS_H_
 
 #include "base/values.h"
-#include "mojo/common/values.mojom.h"
+#include "mojo/common/values.mojom-shared.h"
 #include "mojo/public/cpp/bindings/array_traits.h"
 #include "mojo/public/cpp/bindings/clone_traits.h"
 #include "mojo/public/cpp/bindings/map_traits.h"
@@ -115,6 +115,15 @@ struct CloneTraits<std::unique_ptr<base::DictionaryValue>, false> {
       const std::unique_ptr<base::DictionaryValue>& input);
 };
 
+template <>
+struct StructTraits<common::mojom::NullValueDataView, void*> {
+  static bool IsNull(const void* value) { return true; }
+  static void SetToNull(void** value) {}
+  static bool Read(common::mojom::NullValueDataView data, void** value) {
+    return true;
+  }
+};
+
 template <>
 struct UnionTraits<common::mojom::ValueDataView, base::Value> {
   static common::mojom::ValueDataView::Tag GetTag(const base::Value& data) {
@@ -140,9 +149,7 @@ struct UnionTraits<common::mojom::ValueDataView, base::Value> {
     return common::mojom::ValueDataView::Tag::NULL_VALUE;
   }
 
-  static common::mojom::NullValuePtr null_value(const base::Value& value) {
-    return common::mojom::NullValuePtr();
-  }
+  static void* null_value(const base::Value& value) { return nullptr; }
 
   static bool bool_value(const base::Value& value) {
     bool bool_value{};
@@ -209,8 +216,7 @@ struct UnionTraits<common::mojom::ValueDataView, std::unique_ptr<base::Value>> {
         *value);
   }
 
-  static common::mojom::NullValuePtr null_value(
-      const std::unique_ptr<base::Value>& value) {
+  static void* null_value(const std::unique_ptr<base::Value>& value) {
     return UnionTraits<common::mojom::ValueDataView, base::Value>::null_value(
         *value);
   }

third_party/WebKit/Source/platform/mojo/blink_typemaps.gni

@@ -4,6 +4,7 @@
 
 typemaps = [
   "//mojo/common/file_path.typemap",
+  "//mojo/common/values.typemap",
   "//third_party/WebKit/Source/platform/mojo/File.typemap",
   "//third_party/WebKit/Source/platform/mojo/Geometry.typemap",
   "//third_party/WebKit/Source/platform/mojo/KURL.typemap",