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

webrtc/modules/video_processing/BUILD.gn

 # Copyright (c) 2014 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.
 
 import("//build/config/arm.gni")
 import("../../build/webrtc.gni")
 
 build_video_processing_sse2 = current_cpu == "x86" || current_cpu == "x64"
 
 source_set("video_processing") {
   sources = [
-    "brightness_detection.cc",
-    "brightness_detection.h",
     "content_analysis.cc",
     "content_analysis.h",
-    "deflickering.cc",
-    "deflickering.h",
     "frame_preprocessor.cc",
     "frame_preprocessor.h",
     "include/video_processing.h",
     "include/video_processing_defines.h",
     "spatial_resampler.cc",
     "spatial_resampler.h",
     "util/denoiser_filter.cc",
     "util/denoiser_filter.h",
     "util/denoiser_filter_c.cc",
     "util/denoiser_filter_c.h",
@@ skipping 62 matching lines @@
       "util/denoiser_filter_neon.h",
     ]
     if (current_cpu != "arm64") {
       configs -= [ "//build/config/compiler:compiler_arm_fpu" ]
       cflags = [ "-mfpu=neon" ]
     }
     configs += [ "../..:common_config" ]
     public_configs = [ "../..:common_inherited_config" ]
   }
 }