[remoting host] Simplify capture scheduling logic

This removes an unnecessary section from
WebrtcFrameSchedulerSimple::ScheduleNextFrame()
to address review comments on
https://chromium-review.googlesource.com/940449
and potentially improves performance and b/w utilization.

Bug: 816727
Change-Id: I76aaf326a48f985880ea7ff4ba4e16cc246862b3
Reviewed-on: https://chromium-review.googlesource.com/942484Reviewed-by: Zijie He <zijiehe@chromium.org>
Commit-Queue: Lambros Lambrou <lambroslambrou@chromium.org>
Cr-Commit-Position: refs/heads/master@{#540276}

remoting/protocol/webrtc_frame_scheduler_simple.cc

@@ -252,27 +252,12 @@ void WebrtcFrameSchedulerSimple::ScheduleNextFrame() {
 
   base::TimeTicks target_capture_time;
   if (!last_capture_started_time_.is_null()) {
-    // We won't start sending the frame until last one has been sent.
+    // Try to set the capture time so that (if the estimated processing time is
+    // accurate) the new frame is ready to be sent just when the previous frame
+    // is finished sending.
     target_capture_time = pacing_bucket_.GetEmptyTime() -
         processing_time_estimator_.EstimatedProcessingTime(key_frame_request_);
 
-    // We also try to ensure the next frame will reach the client
-    // |kTargetFrameInterval| after last frame reached.
-
-    // The estimated time when last frame reached or will reach the client.
-    base::TimeTicks estimated_last_frame_reach_time =
-        pacing_bucket_.GetEmptyTime();
-    // The cost of next frame, including both the processing time and transit
-    // time.
-    base::TimeDelta estimated_next_frame_cost =
-        processing_time_estimator_.EstimatedProcessingTime(key_frame_request_) +
-        processing_time_estimator_.EstimatedTransitTime(key_frame_request_);
-    base::TimeTicks ideal_capture_time =
-        estimated_last_frame_reach_time +
-        kTargetFrameInterval -
-        estimated_next_frame_cost;
-    target_capture_time = std::max(target_capture_time, ideal_capture_time);
-
     // Ensure that the capture rate is capped by kTargetFrameInterval, to avoid
     // excessive CPU usage by the capturer.
     target_capture_time = std::max(