remove more CriticalSectionWrappers.

BUG=webrtc:7035

Review-Url: https://codereview.webrtc.org/2779623002
Cr-Commit-Position: refs/heads/master@{#17392}
diff --git a/webrtc/modules/video_coding/media_optimization.cc b/webrtc/modules/video_coding/media_optimization.cc
index fec5c4c..ccd23f6 100644
--- a/webrtc/modules/video_coding/media_optimization.cc
+++ b/webrtc/modules/video_coding/media_optimization.cc
@@ -33,8 +33,7 @@
 };
 
 MediaOptimization::MediaOptimization(Clock* clock)
-    : crit_sect_(CriticalSectionWrapper::CreateCriticalSection()),
-      clock_(clock),
+    : clock_(clock),
       max_bit_rate_(0),
       codec_width_(0),
       codec_height_(0),
@@ -56,7 +55,7 @@
 }
 
 void MediaOptimization::Reset() {
-  CriticalSectionScoped lock(crit_sect_.get());
+  rtc::CritScope lock(&crit_sect_);
   SetEncodingDataInternal(0, 0, 0, 0, 0, 0, max_payload_size_);
   memset(incoming_frame_times_, -1, sizeof(incoming_frame_times_));
   incoming_frame_rate_ = 0.0;
@@ -79,7 +78,7 @@
                                         uint32_t frame_rate,
                                         int num_layers,
                                         int32_t mtu) {
-  CriticalSectionScoped lock(crit_sect_.get());
+  rtc::CritScope lock(&crit_sect_);
   SetEncodingDataInternal(max_bit_rate, frame_rate, target_bitrate, width,
                           height, num_layers, mtu);
 }
@@ -107,7 +106,7 @@
 }
 
 uint32_t MediaOptimization::SetTargetRates(uint32_t target_bitrate) {
-  CriticalSectionScoped lock(crit_sect_.get());
+  rtc::CritScope lock(&crit_sect_);
 
   video_target_bitrate_ = target_bitrate;
 
@@ -125,7 +124,7 @@
 }
 
 uint32_t MediaOptimization::InputFrameRate() {
-  CriticalSectionScoped lock(crit_sect_.get());
+  rtc::CritScope lock(&crit_sect_);
   return InputFrameRateInternal();
 }
 
@@ -137,7 +136,7 @@
 }
 
 uint32_t MediaOptimization::SentFrameRate() {
-  CriticalSectionScoped lock(crit_sect_.get());
+  rtc::CritScope lock(&crit_sect_);
   return SentFrameRateInternal();
 }
 
@@ -148,7 +147,7 @@
 }
 
 uint32_t MediaOptimization::SentBitRate() {
-  CriticalSectionScoped lock(crit_sect_.get());
+  rtc::CritScope lock(&crit_sect_);
   const int64_t now_ms = clock_->TimeInMilliseconds();
   PurgeOldFrameSamples(now_ms);
   UpdateSentBitrate(now_ms);
@@ -159,7 +158,7 @@
     const EncodedImage& encoded_image) {
   size_t encoded_length = encoded_image._length;
   uint32_t timestamp = encoded_image._timeStamp;
-  CriticalSectionScoped lock(crit_sect_.get());
+  rtc::CritScope lock(&crit_sect_);
   const int64_t now_ms = clock_->TimeInMilliseconds();
   PurgeOldFrameSamples(now_ms);
   if (encoded_frame_samples_.size() > 0 &&
@@ -184,12 +183,12 @@
 }
 
 void MediaOptimization::EnableFrameDropper(bool enable) {
-  CriticalSectionScoped lock(crit_sect_.get());
+  rtc::CritScope lock(&crit_sect_);
   frame_dropper_->Enable(enable);
 }
 
 bool MediaOptimization::DropFrame() {
-  CriticalSectionScoped lock(crit_sect_.get());
+  rtc::CritScope lock(&crit_sect_);
   UpdateIncomingFrameRate();
   // Leak appropriate number of bytes.
   frame_dropper_->Leak((uint32_t)(InputFrameRateInternal() + 0.5f));