remoting: remove usage of CapturedFrame.elapsed_time in CastVideoCapturerAdapter

cricket::CapturedFrame.elapsed_time is deprecated since
https://codereview.webrtc.org/1324263004/.

BUG=544125
R=perkj@chromium.org,sergeyu@chromium.org

Review URL: https://codereview.chromium.org/1456083002

Cr-Commit-Position: refs/heads/master@{#360563}

remoting/host/cast_video_capturer_adapter.cc

@@ -45,8 +45,6 @@ void CastVideoCapturerAdapter::OnCaptureCompleted(webrtc::DesktopFrame* frame) {
   captured_frame.width = owned_frame->size().width();
   captured_frame.height = owned_frame->size().height();
   base::TimeTicks current_time = base::TimeTicks::Now();
-  captured_frame.elapsed_time = (current_time - start_time_).InMicroseconds() *
-                                base::Time::kNanosecondsPerMicrosecond;
   captured_frame.time_stamp =
       current_time.ToInternalValue() * base::Time::kNanosecondsPerMicrosecond;
   captured_frame.data = owned_frame->data();
@@ -91,10 +89,6 @@ cricket::CaptureState CastVideoCapturerAdapter::Start(
 
   desktop_capturer_->Start(this);
 
-  // Save the Start() time of |desktop_capturer_|. This will be used
-  // to estimate the creation time of the frame source, to set the elapsed_time
-  // of future CapturedFrames in OnCaptureCompleted().
-  start_time_ = base::TimeTicks::Now();
   capture_timer_.reset(new base::RepeatingTimer());
   capture_timer_->Start(FROM_HERE,
                         base::TimeDelta::FromMicroseconds(

remoting/host/cast_video_capturer_adapter.h

@@ -7,6 +7,7 @@
 
 #include <vector>
 
+#include "base/macros.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/threading/thread_checker.h"
 #include "base/timer/timer.h"
@@ -69,9 +70,6 @@ class CastVideoCapturerAdapter : public cricket::VideoCapturer,
   // Used to schedule periodic screen captures.
   scoped_ptr<base::RepeatingTimer> capture_timer_;
 
-  // Used to set the elapsed_time attribute of captured frames.
-  base::TimeTicks start_time_;
-
   DISALLOW_COPY_AND_ASSIGN(CastVideoCapturerAdapter);
 };