AVFoundation Video Capturer: Remove thread jump when delivering frames

webrtc/base/timestampaligner.h

Index: webrtc/base/timestampaligner.h
diff --git a/webrtc/base/timestampaligner.h b/webrtc/base/timestampaligner.h
index d59c6a4a4e3382e2a245a77915c77e2a75aba7a6..00431f355b809f9b8bc2881e48ee95f9d7d641a4 100644
--- a/webrtc/base/timestampaligner.h
+++ b/webrtc/base/timestampaligner.h
@@ -14,10 +14,11 @@
 #include "webrtc/base/basictypes.h"
 #include "webrtc/base/constructormagic.h"
 #include "webrtc/base/optional.h"
-#include "webrtc/base/thread_checker.h"
 
 namespace rtc {
 
+// This class is not thread safe, so all calls to it must be synchronized
+// externally.
 class TimestampAligner {
  public:
   TimestampAligner();
@@ -30,8 +31,6 @@ class TimestampAligner {
   int64_t ClipTimestamp(int64_t filtered_time_us, int64_t system_time_us);
 
  private:
-  rtc::ThreadChecker thread_checker_;
-
   // State for the timestamp translation.
   int frames_seen_;
   // Estimated offset between camera time and system monotonic time.