ImageCapture: support exposure mode configuration

media/mojo/interfaces/image_capture.mojom

 // 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.
 
 module media.mojom;
 
 // Equivalent to idl MediaSettingsRange, arbitrary range representing the
 // allowed variations of a Capability or an Option.
 // https://w3c.github.io/mediacapture-image/#mediasettingsrange
 struct Range {
   uint32 max;
   uint32 min;
   uint32 current;
 };
 
-// https://w3c.github.io/mediacapture-image/#idl-def-FocusMode
-enum FocusMode { UNAVAILABLE, MANUAL, SINGLE_SHOT, CONTINUOUS };
+// https://w3c.github.io/mediacapture-image/#idl-def-MeteringMode
+enum MeteringMode { UNAVAILABLE, MANUAL, SINGLE_SHOT, CONTINUOUS };
 
 // Equivalent to idl PhotoCapabilities,
 // https://w3c.github.io/mediacapture-image/#photocapabilities
 struct PhotoCapabilities {
   Range iso;
   Range height;
   Range width;
   Range zoom;
-  FocusMode focus_mode;
+  MeteringMode focus_mode;
+  MeteringMode exposure_mode;
 };
 
 // Equivalent to idl Point2D.
 // TODO(mcasas): use gfx::mojom::PointF after https://crbug.com/640049.
 struct Point2D {
   float x;
   float y;
 };
 
 // Equivalent to idl PhotoSettings,
 // https://w3c.github.io/mediacapture-image/index.html#photosettings
 struct PhotoSettings {
   // uint32 cannot be nullable, i.e. uint32? does not work, use instead a flag.
   bool has_zoom;
   uint32 zoom;
   bool has_width;
   uint32 width;
   bool has_height;
   uint32 height;
   bool has_focus_mode;
-  FocusMode focus_mode;
+  MeteringMode focus_mode;
+  bool has_exposure_mode;
+  MeteringMode exposure_mode;
   array<Point2D> points_of_interest;
 };
 
 // This is a mojo move-only equivalent of a Blob, i.e. MIME type and Data.
 struct Blob {
   string mime_type;
   array<uint8> data;
 };
 
 // |source_id| is the renderer-side UUID identifier of the image capture device.
 interface ImageCapture
 {
     // Retrieves the image capture device capabilities and current settings.
     // https://w3c.github.io/mediacapture-image/index.html#widl-ImageCapture-getPhotoCapabilities-Promise-PhotoCapabilities
     GetCapabilities(string source_id)
         => (PhotoCapabilities capabilities);
 
     // Sets the |settings| on the associated video capture device.
     // https://w3c.github.io/mediacapture-image/index.html#widl-ImageCapture-setOptions-Promise-void--PhotoSettings-photoSettings
     SetOptions(string source_id, PhotoSettings settings)
         => (bool success);
 
     // Takes a Photo from the given |source_id|, returning it encoded in |blob|
     // with the format specified in its |mime_type|.
     // https://w3c.github.io/mediacapture-image/index.html#widl-ImageCapture-takePhoto-Promise-Blob
     TakePhoto(string source_id)
         => (Blob blob);
 };