Record the TaskLatency Histogram in Microseconds Instead of Milliseconds

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 d476b29069e83525241378e66c58b9d231e3693f..95e4510532c063fb05462b3fc64af050a3dd00fd 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -74300,7 +74300,21 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   </summary>
 </histogram>
 
-<histogram name="TaskScheduler.TaskLatency" units="ms">
+<histogram base="true" name="TaskScheduler.TaskLatency" units="ms">
+  <obsolete>
+    Deprecated 4/2017. Units changed from milliseconds to microseconds.
+  </obsolete>
+  <owner>fdoray@chromium.org</owner>
+  <owner>gab@chromium.org</owner>
+  <owner>robliao@chromium.org</owner>
+  <summary>
+    Time elapsed between when a task is posted and when it starts to run.
+    Recorded for each task that runs inside the TaskScheduler.
+  </summary>
+</histogram>
+
+<histogram base="true" name="TaskScheduler.TaskLatencyMicroseconds"
+    units="microseconds">
   <owner>fdoray@chromium.org</owner>
   <owner>gab@chromium.org</owner>
   <owner>robliao@chromium.org</owner>
@@ -127429,6 +127443,12 @@ from previous Chrome versions.
   <affected-histogram
       name="TaskScheduler.TaskLatency.UserBlockingTaskPriority"/>
   <affected-histogram name="TaskScheduler.TaskLatency.UserVisibleTaskPriority"/>
+  <affected-histogram
+      name="TaskScheduler.TaskLatencyMicroseconds.BackgroundTaskPriority"/>
+  <affected-histogram
+      name="TaskScheduler.TaskLatencyMicroseconds.UserBlockingTaskPriority"/>
+  <affected-histogram
+      name="TaskScheduler.TaskLatencyMicroseconds.UserVisibleTaskPriority"/>
 </histogram_suffixes>
 
 <histogram_suffixes name="TaskSchedulerTaskPriority" separator=".">
@@ -127459,6 +127479,7 @@ from previous Chrome versions.
       Deprecated 12/2016. Pool name removed from task latency histogram name.
     </obsolete>
   </affected-histogram>
+  <affected-histogram name="TaskScheduler.TaskLatencyMicroseconds"/>
 </histogram_suffixes>
 
 <histogram_suffixes name="TaskSchedulerWorkerPool" separator=".">