mojo: Support deserialize mojom struct from binary data in JS

This CL adds --js_deserializable_struct=gpu.mojom.VulkanInfo param
for mojom binding generator to allow generating  js deserialize
method for specified mojom struct.

Bug: 887018
Change-Id: I98f2224e7422d52fb0c4aeb684078dd191f8e616
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1869685Reviewed-by: Ken Rockot <rockot@google.com>
Commit-Queue: Peng Huang <penghuang@chromium.org>
Cr-Commit-Position: refs/heads/master@{#710098}

mojo/public/interfaces/bindings/tests/BUILD.gn

@@ -274,6 +274,15 @@ action_foreach("validation_test_data_list") {
   ]
 }
 
+mojom("test_deserializer_interface") {
+  testonly = true
+  generate_java = true
+  sources = [
+    "deserializer.test-mojom",
+  ]
+  js_generate_struct_deserializers = true
+}
+
 mojom("test_interfaces") {
   testonly = true
   generate_java = true
@@ -300,6 +309,7 @@ mojom("test_interfaces") {
   ]
   public_deps = [
     ":echo",
+    ":test_deserializer_interface",
     ":test_mojom_import",
     ":test_mojom_import2",
     "//mojo/public/mojom/base",

mojo/public/interfaces/bindings/tests/deserializer.test-mojom

+// Copyright 2019 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 deserializer;
+
+struct TestStruct {
+  int32 v1;
+  int32 v2;
+  int64 v3;
+};

mojo/public/js/bindings_lite.js

@@ -1330,6 +1330,22 @@ mojo.internal.Struct = function(objectToBlessAsType, name, packedSize, fields) {
   };
 };
 
+/**
+ * @param {!mojo.internal.MojomType} structMojomType
+ * @return {!Function}
+ * @export
+ */
+mojo.internal.createStructDeserializer = function(structMojomType) {
+  return function(dataView) {
+    if (structMojomType.$ == undefined ||
+        structMojomType.$.structSpec == undefined) {
+      throw new Error("Invalid struct mojom type!");
+    }
+    const decoder = new mojo.internal.Decoder(dataView, []);
+    return decoder.decodeStructInline(structMojomType.$.structSpec);
+  };
+};
+
 /**
  * @param {!Object} objectToBlessAsUnion
  * @param {string} name

mojo/public/tools/bindings/generators/js_templates/lite/struct_definition.tmpl

@@ -33,6 +33,11 @@ mojo.internal.Struct(
 {%- endfor %}
     ]);
 
+{% if generate_struct_deserializers %}
+{{module.namespace}}.{{struct.name}}_Deserialize =
+    mojo.internal.createStructDeserializer({{module.namespace}}.{{struct.name}}Spec.$);
+{% endif %}
+
 {%  if generate_closure_exports -%}
 goog.provide('{{module.namespace}}.{{struct.name}}');
 

mojo/public/tools/bindings/generators/mojom_js_generator.py

@@ -264,6 +264,7 @@ class Generator(generator.Generator):
       "unions": self.module.unions,
       "generate_fuzzing": self.generate_fuzzing,
       "generate_closure_exports": for_compile,
+      "generate_struct_deserializers": self.js_generate_struct_deserializers,
    }
 
   @staticmethod

mojo/public/tools/bindings/mojom.gni

@@ -294,6 +294,9 @@ if (enable_mojom_typemapping) {
 #   use_typescript_sources (optional)
 #       Uses the Typescript generator to generate JavaScript bindings.
 #
+#   js_generate_struct_deserializers (optiona)
+#       Generates JS deerialize methods for structs.
+#
 # The following parameters are used to support the component build. They are
 # needed so that bindings which are linked with a component can use the same
 # export settings for classes. The first three are for the chromium variant, and
@@ -1283,6 +1286,11 @@ template("mojom") {
           "--js_bindings_mode=new",
         ]
 
+        if (defined(invoker.js_generate_struct_deserializers) &&
+            invoker.js_generate_struct_deserializers) {
+          args += [ "--js_generate_struct_deserializers" ]
+        }
+
         if (!defined(invoker.scramble_message_ids) ||
             invoker.scramble_message_ids) {
           inputs += message_scrambling_inputs

mojo/public/tools/bindings/mojom_bindings_generator.py

@@ -219,6 +219,8 @@ class MojomProcessor(object):
             variant=args.variant, bytecode_path=args.bytecode_path,
             for_blink=args.for_blink,
             js_bindings_mode=args.js_bindings_mode,
+            js_generate_struct_deserializers=\
+                    args.js_generate_struct_deserializers,
             export_attribute=args.export_attribute,
             export_header=args.export_header,
             generate_non_variant_code=args.generate_non_variant_code,
@@ -470,6 +472,10 @@ def main():
       help="This option only affects the JavaScript bindings. The value could "
       "be \"new\" to generate new-style lite JS bindings in addition to the "
       "old, or \"old\" to only generate old bindings.")
+  generate_parser.add_argument(
+      "--js_generate_struct_deserializers", action="store_true",
+      help="Generate javascript deserialize methods for structs in "
+      "mojom-lite.js file")
   generate_parser.add_argument(
       "--export_attribute", default="",
       help="Optional attribute to specify on class declaration to export it "

mojo/public/tools/bindings/pylib/mojom/generate/generator.py

@@ -194,6 +194,7 @@ class Generator(object):
   def __init__(self, module, output_dir=None, typemap=None, variant=None,
                bytecode_path=None, for_blink=False,
                js_bindings_mode="new",
+               js_generate_struct_deserializers=False,
                export_attribute=None,
                export_header=None, generate_non_variant_code=False,
                support_lazy_serialization=False, disallow_native_types=False,
@@ -206,6 +207,7 @@ class Generator(object):
     self.bytecode_path = bytecode_path
     self.for_blink = for_blink
     self.js_bindings_mode = js_bindings_mode
+    self.js_generate_struct_deserializers = js_generate_struct_deserializers
     self.export_attribute = export_attribute
     self.export_header = export_header
     self.generate_non_variant_code = generate_non_variant_code

third_party/blink/web_tests/http/tests/mojo/deserializer.html

+<!DOCTYPE html>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script src="/gen/layout_test_data/mojo/public/js/mojo_bindings_lite.js"></script>
+<script src="/gen/mojo/public/interfaces/bindings/tests/deserializer.test-mojom-lite.js"></script>
+<script>
+'use strict';
+
+test(() => {
+  const data = new Uint32Array([
+    0, 0,     // header
+    8899,     // v1
+    9988,     // v2
+    7777, 0   // v3
+    ]);
+  const dataview = new DataView(data.buffer);
+  const s = deserializer.TestStruct_Deserialize(dataview);
+  assert_equals(s.v1, 8899);
+  assert_equals(s.v2, 9988);
+  assert_equals(s.v3, 7777);
+}, 'deserializer');
+
+</script>