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

tools/metrics/histograms/histograms.xml

Index: tools/metrics/histograms/histograms.xml
diff --git a/tools/metrics/histograms/histograms.xml b/tools/metrics/histograms/histograms.xml
index bbd794ca924a4d5f13a55352c9ccb7f39d12d193..2b79ecce91a197918738cdce5151e24b370fa707 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -4101,6 +4101,24 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   </summary>
 </histogram>
 
+<histogram name="Chromoting.Video.CaptureOverhead" units="ms">
+  <owner>anandc@chromium.org</owner>
+  <owner>sergeyu@chromium.org</owner>
+  <summary>
+    Amount of time wasted on IPC and threading overhead when capturing a video
+    frame.
+  </summary>
+</histogram>
+
+<histogram name="Chromoting.Video.CapturePendingLatency" units="ms">
+  <owner>anandc@chromium.org</owner>
+  <owner>sergeyu@chromium.org</owner>
+  <summary>
+    The time from when an input event is received to when the next frame is
+    captured.
+  </summary>
+</histogram>
+
 <histogram name="Chromoting.Video.DecodeLatency" units="ms">
   <owner>anandc@chromium.org</owner>
   <owner>sergeyu@chromium.org</owner>
@@ -4116,6 +4134,14 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   </summary>
 </histogram>
 
+<histogram name="Chromoting.Video.EncodePendingLatency" units="ms">
+  <owner>anandc@chromium.org</owner>
+  <owner>sergeyu@chromium.org</owner>
+  <summary>
+    Delay before a newly captured frame is passed to the encoder.
+  </summary>
+</histogram>
+
 <histogram name="Chromoting.Video.FrameRate" units="fps">
   <owner>anandc@chromium.org</owner>
   <owner>sergeyu@chromium.org</owner>
@@ -4149,6 +4175,14 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   </summary>
 </histogram>
 
+<histogram name="Chromoting.Video.SendPendingLatency" units="ms">
+  <owner>anandc@chromium.org</owner>
+  <owner>sergeyu@chromium.org</owner>
+  <summary>
+    Delay before an encoded video packet is written to the send buffer.
+  </summary>
+</histogram>
+
 <histogram name="clickjacking.discard_download" units="ms">
   <owner>Please list the metric's owners. Add more owner tags as needed.</owner>
   <summary>