Use int64_t more consistently for times, in particular for RTT values.

Existing code was inconsistent about whether to use uint16_t, int, unsigned int,
or uint32_t, and sometimes silently truncated one to another, or truncated
int64_t.  Because most core time-handling functions use int64_t, being
consistent about using int64_t unless otherwise necessary minimizes the number
of explicit or implicit casts.

BUG=chromium:81439
TEST=none
R=henrik.lundin@webrtc.org, holmer@google.com, tommi@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/31349004

git-svn-id: http://webrtc.googlecode.com/svn/trunk@8045 4adac7df-926f-26a2-2b94-8c16560cd09d

webrtc/modules/video_coding/codecs/i420/main/interface/i420.h

@@ -73,7 +73,7 @@ class I420Encoder : public VideoEncoder {
   }
 
   virtual int SetChannelParameters(uint32_t /*packetLoss*/,
-                                   int /*rtt*/) OVERRIDE {
+                                   int64_t /*rtt*/) OVERRIDE {
     return WEBRTC_VIDEO_CODEC_OK;
   }