Define StructTraits for content::MediaDeviceInfo

This CL introduces Mojom struct for content::MediaDeviceInfo and removes
its IPC_STRUCT_TRAITS in favor of StructTraits.
This is in preparation for migration of MediaDevices.enumerateDevices()
processing from content to Blink.

Bug: 764680
Change-Id: Idc17f1b53963d2fb7a80b4ac98890913cb5ad521
Reviewed-on: https://chromium-review.googlesource.com/807840
Commit-Queue: Chandan Padhi <c.padhi@samsung.com>
Reviewed-by: Guido Urdaneta <guidou@chromium.org>
Reviewed-by: Avi Drissman <avi@chromium.org>
Reviewed-by: Tom Sepez <tsepez@chromium.org>
Cr-Commit-Position: refs/heads/master@{#521977}

content/common/BUILD.gn

@@ -211,8 +211,6 @@ source_set("common") {
     "media/cdm_info.cc",
     "media/media_devices.cc",
     "media/media_devices.h",
-    "media/media_devices_param_traits.cc",
-    "media/media_devices_param_traits.h",
     "media/media_player_delegate_messages.h",
     "media/media_player_messages_android.h",
     "media/media_stream_controls.cc",

content/common/media/media_devices.typemap

@@ -4,10 +4,7 @@
 
 mojom = "//third_party/WebKit/public/platform/modules/mediastream/media_devices.mojom"
 public_headers = [ "//content/common/media/media_devices.h" ]
-traits_headers = [
-  "//content/common/media/media_devices_param_traits.h",
-  "//content/common/media/media_devices_typemap_traits.h",
-]
+traits_headers = [ "//content/common/media/media_devices_typemap_traits.h" ]
 sources = [
   "//content/common/media/media_devices_typemap_traits.cc",
 ]

content/common/media/media_devices_param_traits.cc

-// Copyright 2016 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 "content/common/media/media_devices_param_traits.h"
-
-// Generate param traits write methods.
-#include "ipc/param_traits_write_macros.h"
-namespace IPC {
-#include "content/common/media/media_devices_param_traits.h"
-}  // namespace IPC
-
-// Generate param traits read methods.
-#include "ipc/param_traits_read_macros.h"
-namespace IPC {
-#include "content/common/media/media_devices_param_traits.h"
-}  // namespace IPC
-
-// Generate param traits log methods.
-#include "ipc/param_traits_log_macros.h"
-namespace IPC {
-#include "content/common/media/media_devices_param_traits.h"
-}  // namespace IPC

content/common/media/media_devices_param_traits.h

-// Copyright 2016 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.
-
-// Multiply-included IPC traits file, hence no include guard.
-
-#include "content/common/content_export.h"
-#include "content/common/media/media_devices.h"
-#include "ipc/ipc_message_macros.h"
-
-#undef IPC_MESSAGE_EXPORT
-#define IPC_MESSAGE_EXPORT CONTENT_EXPORT
-
-IPC_STRUCT_TRAITS_BEGIN(content::MediaDeviceInfo)
-  IPC_STRUCT_TRAITS_MEMBER(device_id)
-  IPC_STRUCT_TRAITS_MEMBER(label)
-  IPC_STRUCT_TRAITS_MEMBER(group_id)
-IPC_STRUCT_TRAITS_END()

content/common/media/media_devices_typemap_traits.cc

@@ -47,4 +47,18 @@ bool EnumTraits<blink::mojom::MediaDeviceType, content::MediaDeviceType>::
   return false;
 }
 
+// static
+bool StructTraits<
+    blink::mojom::MediaDeviceInfoDataView,
+    content::MediaDeviceInfo>::Read(blink::mojom::MediaDeviceInfoDataView input,
+                                    content::MediaDeviceInfo* out) {
+  if (!input.ReadDeviceId(&out->device_id))
+    return false;
+  if (!input.ReadLabel(&out->label))
+    return false;
+  if (!input.ReadGroupId(&out->group_id))
+    return false;
+  return true;
+}
+
 }  // namespace mojo

content/common/media/media_devices_typemap_traits.h

@@ -18,6 +18,25 @@ struct EnumTraits<blink::mojom::MediaDeviceType, content::MediaDeviceType> {
                         content::MediaDeviceType* out);
 };
 
+template <>
+struct StructTraits<blink::mojom::MediaDeviceInfoDataView,
+                    content::MediaDeviceInfo> {
+  static const std::string& device_id(const content::MediaDeviceInfo& info) {
+    return info.device_id;
+  }
+
+  static const std::string& label(const content::MediaDeviceInfo& info) {
+    return info.label;
+  }
+
+  static const std::string& group_id(const content::MediaDeviceInfo& info) {
+    return info.group_id;
+  }
+
+  static bool Read(blink::mojom::MediaDeviceInfoDataView input,
+                   content::MediaDeviceInfo* out);
+};
+
 }  // namespace mojo
 
 #endif  // CONTENT_COMMON_MEDIA_MEDIA_DEVICES_TYPEMAP_TRAITS_H_
\ No newline at end of file

third_party/WebKit/public/platform/modules/mediastream/media_devices.mojom

@@ -7,9 +7,6 @@ module blink.mojom;
 import "media/capture/mojo/video_capture_types.mojom";
 import "media/mojo/interfaces/audio_parameters.mojom";
 
-[Native]
-struct MediaDeviceInfo;
-
 enum MediaDeviceType {
   MEDIA_AUDIO_INPUT,
   MEDIA_VIDEO_INPUT,
@@ -23,6 +20,12 @@ enum MediaDeviceType {
 // JavaScript.
 enum FacingMode { NONE, USER, ENVIRONMENT, LEFT, RIGHT };
 
+struct MediaDeviceInfo {
+  string device_id;
+  string label;
+  string group_id;
+};
+
 struct VideoInputDeviceCapabilities {
   string device_id;
   array<media.mojom.VideoCaptureFormat> formats;