[Mojo Video Capture] Hook up video capture service behind a feature flag

content/browser/renderer_host/media/video_capture_provider.h

 // Copyright 2017 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.
 
 #ifndef CONTENT_BROWSER_RENDERER_HOST_MEDIA_BUILDABLE_VIDEO_CAPTURE_DEVICE_H_
 #define CONTENT_BROWSER_RENDERER_HOST_MEDIA_BUILDABLE_VIDEO_CAPTURE_DEVICE_H_
 
 #include "base/memory/ptr_util.h"
 #include "base/memory/ref_counted.h"
 #include "content/common/content_export.h"
@@ skipping 50 matching lines @@
       media::VideoCaptureDevice::TakePhotoCallback callback) = 0;
   virtual void MaybeSuspendDevice() = 0;
   virtual void ResumeDevice() = 0;
   virtual void RequestRefreshFrame() = 0;
 
   // Methods for specific types of devices.
   virtual void SetDesktopCaptureWindowIdAsync(gfx::NativeViewId window_id,
                                               base::OnceClosure done_cb) = 0;
 };
 
+// Note: GetDeviceInfosAsync is only relevant for devices with
+// MediaStreamType == MEDIA_DEVICE_VIDEO_CAPTURE, i.e. camera devices.
 class CONTENT_EXPORT VideoCaptureProvider {
  public:
+  using GetDeviceInfosCallback =
+      base::Callback<void(const std::vector<media::VideoCaptureDeviceInfo>&)>;
+
   virtual ~VideoCaptureProvider() {}
 
   virtual void Uninitialize() = 0;
 
   // The passed-in |result_callback| must guarantee that the called
   // instance stays alive until |result_callback| is invoked.
   virtual void GetDeviceInfosAsync(
-      const base::Callback<
-          void(const std::vector<media::VideoCaptureDeviceInfo>&)>&
-          result_callback) = 0;
+      const GetDeviceInfosCallback& result_callback) = 0;
 
   virtual std::unique_ptr<VideoCaptureDeviceLauncher>
   CreateDeviceLauncher() = 0;
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_RENDERER_HOST_MEDIA_BUILDABLE_VIDEO_CAPTURE_DEVICE_H_