[Mojo Video Capture] Simplify API and some cleanups

services/video_capture/public/interfaces/video_capture_settings_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 "services/video_capture/public/interfaces/video_capture_settings_traits.h"
+
+#include "media/capture/mojo/video_capture_types_typemap_traits.h"
+#include "ui/gfx/geometry/mojo/geometry_struct_traits.h"
+
+namespace mojo {
+
+// static
+bool StructTraits<video_capture::mojom::VideoCaptureFormatDataView,
+                  video_capture::VideoCaptureFormat>::
+    Read(video_capture::mojom::VideoCaptureFormatDataView data,
+         video_capture::VideoCaptureFormat* out) {
+  if (!data.ReadFrameSize(&out->frame_size))
+    return false;
+  out->frame_rate = data.frame_rate();
+  return true;
+}
+
+// static
+bool StructTraits<video_capture::mojom::VideoCaptureSettingsDataView,
+                  video_capture::VideoCaptureSettings>::
+    Read(video_capture::mojom::VideoCaptureSettingsDataView data,
+         video_capture::VideoCaptureSettings* out) {
+  if (!data.ReadFormat(&out->format))
+    return false;
+  if (!data.ReadResolutionChangePolicy(&out->resolution_change_policy))
+    return false;
+  if (!data.ReadPowerLineFrequency(&out->power_line_frequency))
+    return false;
+  return true;
+}
+
+
+}  // namespace mojo