Delete unused methods of the VideoProcessing class. And fix a typo.

webrtc/modules/video_processing/video_processing.gypi

 # Copyright (c) 2011 The WebRTC project authors. All Rights Reserved.
 #
 # Use of this source code is governed by a BSD-style license
 # that can be found in the LICENSE file in the root of the source
 # tree. An additional intellectual property rights grant can be found
 # in the file PATENTS.  All contributing project authors may
 # be found in the AUTHORS file in the root of the source tree.
 
 {
   'targets': [
     {
       'target_name': 'video_processing',
       'type': 'static_library',
       'dependencies': [
         'webrtc_utility',
         '<(webrtc_root)/common_audio/common_audio.gyp:common_audio',
         '<(webrtc_root)/common_video/common_video.gyp:common_video',
         '<(webrtc_root)/system_wrappers/system_wrappers.gyp:system_wrappers',
       ],
       'sources': [
         'include/video_processing.h',
         'include/video_processing_defines.h',
-        'brightness_detection.cc',
-        'brightness_detection.h',
         'content_analysis.cc',
         'content_analysis.h',
-        'deflickering.cc',
-        'deflickering.h',
         'frame_preprocessor.cc',
         'frame_preprocessor.h',
         'spatial_resampler.cc',
         'spatial_resampler.h',
         'video_decimator.cc',
         'video_decimator.h',
         'video_processing_impl.cc',
         'video_processing_impl.h',
         'video_denoiser.cc',
         'video_denoiser.h',
@@ skipping 49 matching lines @@
           'sources': [
             'util/denoiser_filter_neon.cc',
             'util/denoiser_filter_neon.h',
           ],
         },
       ],
     }],
   ],
 }