Media Stream Image Capture (4): wire takePhoto and implement in FakeVCDevice

media/capture/video/video_capture_device.h

 // Copyright (c) 2012 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.
 //
 // VideoCaptureDevice is the abstract base class for realizing video capture
 // device support in Chromium. It provides the interface for OS dependent
 // implementations.
 // The class is created and functions are invoked on a thread owned by
 // VideoCaptureManager. Capturing is done on other threads, depending on the OS
 // specific implementation.
@@ skipping 281 matching lines @@
   // hardware into a state where other applications could use it, free the
   // memory associated with capture, and delete the |client| pointer passed into
   // AllocateAndStart.
   //
   // If deallocation is done asynchronously, then the device implementation must
   // ensure that a subsequent AllocateAndStart() operation targeting the same ID
   // would be sequenced through the same task runner, so that deallocation
   // happens first.
   virtual void StopAndDeAllocate() = 0;
 
+  // Asynchronously takes a photo, possibly reconfiguring the capture objects
+  // and/or interrupting the capture flow. Returns false if taking the picture
+  // could not be scheduled at all, or else runs |photo_callback| (on the thread
+  // where TakePhoto() is run).
+  using TakePhotoCallback =
+      base::Callback<void(const std::string&, std::unique_ptr<std::string>)>;
+  virtual bool TakePhoto(const TakePhotoCallback& photo_callback);

[miu, 2016/05/04 23:45:50]

Consider adding WARN_UNUSED_RESULT (just before the ending semicolon) to make
sure callers check and handle the "fail" boolean result.

[mcasas, 2016/05/05 00:57:12]

Done.

+
   // Gets the power line frequency, either from the params if specified by the
   // user or from the current system time zone.
   PowerLineFrequency GetPowerLineFrequency(
       const VideoCaptureParams& params) const;
 
  private:
   // Gets the power line frequency from the current system time zone if this is
   // defined, otherwise returns 0.
   PowerLineFrequency GetPowerLineFrequencyForLocation() const;
 };
 
 }  // namespace media
 
 #endif  // MEDIA_VIDEO_CAPTURE_VIDEO_CAPTURE_DEVICE_H_