Enable cpplint for webrtc/audio and webrtc/call, and fix all uncovered cpplint errors.

BUG=webrtc:5268,webrtc:5273
TESTED=Fixed issues reported by:
find webrtc/audio -type f -name *.cc -o -name *.h | xargs cpplint.py
find webrtc/call -type f -name *.cc -o -name *.h | xargs cpplint.py
followed by 'git cl presubmit'.

R=kjellander@webrtc.org, pbos@webrtc.org

Review URL: https://codereview.webrtc.org/1483323002 .

Cr-Commit-Position: refs/heads/master@{#10853}

PRESUBMIT.py

@@ -16,6 +16,8 @@ import sys
 
 # Directories that will be scanned by cpplint by the presubmit script.
 CPPLINT_DIRS = [
+  'webrtc/audio',
+  'webrtc/call',
   'webrtc/video_engine',
 ]
 

webrtc/audio/audio_receive_stream_unittest.cc

@@ -8,6 +8,8 @@
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
+#include <string>
+
 #include "testing/gtest/include/gtest/gtest.h"
 
 #include "webrtc/audio/audio_receive_stream.h"

webrtc/audio/audio_send_stream_unittest.cc

@@ -8,6 +8,9 @@
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
+#include <string>
+#include <vector>
+
 #include "testing/gtest/include/gtest/gtest.h"
 
 #include "webrtc/audio/audio_send_stream.h"

webrtc/call/rtc_event_log_unittest.cc

@@ -11,6 +11,7 @@
 #ifdef ENABLE_RTC_EVENT_LOG
 
 #include <string>
+#include <utility>
 #include <vector>
 
 #include "testing/gtest/include/gtest/gtest.h"