Add UMA histograms for more detailed latency tracking on the CRD host.

Previously only two delays in CRD hosts were tracked: capture time and
encode time. This CL adds 4 other values that are now measured on the
host, sent to the client and logged to UMA:
 - capture_pending_time: time between input event being received and
    when the next frame starts capturing.
 - capture_overhead_time: extra latency for the capturer caused by IPC
    and threading.
 - encode_pending_time: delay between capturer and encoder.
 - send_pending_time: time encoded packets wait in the send queue.

VideoFramePump is responsible for measuring all latency values sent to
the client except for capture_time_ms which is still measured by the
capturer.

Review URL: https://codereview.chromium.org/1365663003

Cr-Commit-Position: refs/heads/master@{#351504}

4 files changed, 2 insertions, 17 deletions

diff --git a/remoting/codec/video_encoder_helper.cc b/remoting/codec/video_encoder_helper.cc
index 5310d01..288ec72a 100644
--- a/remoting/codec/video_encoder_helper.cc
+++ b/remoting/codec/video_encoder_helper.cc
@@ -57,8 +57,7 @@ VideoEncoderHelper::CreateVideoPacketWithUpdatedRegion(
     }
   }
 
-  // Store the capture time and frame DPI.
-  packet->set_capture_time_ms(frame.capture_time_ms());
+  // Store frame DPI.
   if (!frame.dpi().is_zero()) {
     packet->mutable_format()->set_x_dpi(frame.dpi().x());
     packet->mutable_format()->set_y_dpi(frame.dpi().y());
diff --git a/remoting/codec/video_encoder_helper_unittest.cc b/remoting/codec/video_encoder_helper_unittest.cc
index e464802..569ecac 100644
--- a/remoting/codec/video_encoder_helper_unittest.cc
+++ b/remoting/codec/video_encoder_helper_unittest.cc
@@ -36,7 +36,6 @@ TEST(VideoEncoderHelperTest, PropagatesCommonFields) {
   EXPECT_TRUE(packet->format().has_x_dpi());
   EXPECT_TRUE(packet->format().has_y_dpi());
 
-  EXPECT_TRUE(packet->has_capture_time_ms());
   EXPECT_EQ(1, packet->dirty_rects().size());
 
   ASSERT_TRUE(packet->has_use_desktop_shape());
diff --git a/remoting/codec/video_encoder_verbatim.cc b/remoting/codec/video_encoder_verbatim.cc
index 2948e3e..8d1befb 100644
--- a/remoting/codec/video_encoder_verbatim.cc
+++ b/remoting/codec/video_encoder_verbatim.cc
@@ -6,7 +6,6 @@
 
 #include "base/logging.h"
 #include "base/stl_util.h"
-#include "base/time/time.h"
 #include "remoting/base/util.h"
 #include "remoting/proto/video.pb.h"
 #include "third_party/webrtc/modules/desktop_capture/desktop_frame.h"
@@ -32,8 +31,6 @@ scoped_ptr<VideoPacket> VideoEncoderVerbatim::Encode(
   if (frame.updated_region().is_empty())
     return nullptr;
 
-  base::Time encode_start_time = base::Time::Now();
-
   // Create a VideoPacket with common fields (e.g. DPI, rects, shape) set.
   scoped_ptr<VideoPacket> packet(helper_.CreateVideoPacket(frame));
   packet->mutable_format()->set_encoding(VideoPacketFormat::ENCODING_VERBATIM);
@@ -64,10 +61,6 @@ scoped_ptr<VideoPacket> VideoEncoderVerbatim::Encode(
     }
   }
 
-  // Note the time taken to encode the pixel data.
-  packet->set_encode_time_ms(
-      (base::Time::Now() - encode_start_time).InMillisecondsRoundedUp());
-
   return packet.Pass();
 }
 
diff --git a/remoting/codec/video_encoder_vpx.cc b/remoting/codec/video_encoder_vpx.cc
index 1fa19a4..0dcd456 100644
--- a/remoting/codec/video_encoder_vpx.cc
+++ b/remoting/codec/video_encoder_vpx.cc
@@ -270,8 +270,6 @@ scoped_ptr<VideoPacket> VideoEncoderVpx::Encode(
   if (frame.updated_region().is_empty() && !encode_unchanged_frame_)
     return nullptr;
 
-  base::TimeTicks encode_start_time = base::TimeTicks::Now();
-
   // Create or reconfigure the codec to match the size of |frame|.
   if (!codec_ ||
       (image_ &&
@@ -296,7 +294,7 @@ scoped_ptr<VideoPacket> VideoEncoderVpx::Encode(
   }
 
   // Do the actual encoding.
-  int timestamp = (encode_start_time - timestamp_base_).InMilliseconds();
+  int timestamp = (base::TimeTicks::Now() - timestamp_base_).InMilliseconds();
   vpx_codec_err_t ret = vpx_codec_encode(
       codec_.get(), image_.get(), timestamp, 1, 0, VPX_DL_REALTIME);
   DCHECK_EQ(ret, VPX_CODEC_OK)
@@ -341,10 +339,6 @@ scoped_ptr<VideoPacket> VideoEncoderVpx::Encode(
     }
   }
 
-  // Note the time taken to encode the pixel data.
-  packet->set_encode_time_ms(
-      (base::TimeTicks::Now() - encode_start_time).InMillisecondsRoundedUp());
-
   return packet.Pass();
 }