Record resource scheduler UMA

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 940a002fe71465c80c3e52b7f1484e37fadfa6fb..db56c193f7e27b2206ff60917e951508143fb3f0 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -60273,6 +60273,23 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   </summary>
 </histogram>
 
+<histogram name="ResourceScheduler.PeakDelayableRequestsInFlight"
+    units="requests">
+  <owner>tbansal@chromium.org</owner>
+  <summary>
+    Records the highest number of delayable requests that were in-flight when
+    the given request with higher priority was in-flight.
+  </summary>
+</histogram>
+
+<histogram name="ResourceScheduler.RequestsCount" units="requests count">
+  <owner>tbansal@chromium.org</owner>
+  <summary>
+    Records the count of number of requests in-flight. Recorded when the set of
+    in-flight requests is modified by the resource scheduler.
+  </summary>
+</histogram>
+
 <histogram name="ResourceScheduler.RequestTimeDeferred.Active">
   <obsolete>
     Deprecated 1/2016
@@ -91539,6 +91556,35 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
       name="ResourceScheduler.ClientLoadedTime.Other.SwitchedToActive"/>
 </histogram_suffixes>
 
+<histogram_suffixes name="ResourceSchedulerPeakDelayableRequestsInFlight">
+  <suffix name="LayoutBlocking"
+      label="Records the highest number of non-delayable requests that were
+             in-flight at the same time when a layout blocking request was
+             in-flight. Recorded every time a layout blocking request
+             finishes."/>
+  <suffix name="NonDelayable"
+      label="Records the highest number of non-delayable requests that were
+             in-flight at the same time when a non-delayable request was
+             in-flight. Recorded every time a non-delayable request finishes."/>
+  <affected-histogram name="ResourceScheduler.PeakDelayableRequestsInFlight"/>
+</histogram_suffixes>
+
+<histogram_suffixes name="ResourceSchedulerRequestsCount">
+  <suffix name="All" label="All requests in-flight were counted."/>
+  <suffix name="Delayable" label="Delayable requests in-flight were counted."/>
+  <suffix name="NonDelayable"
+      label="Non-delayable requests in-flight were counted."/>
+  <suffix name="TotalLayoutBlocking"
+      label="Layout blocking requests in-flight were counted."/>
+  <suffix name="DelayableWhenLayoutBlocking"
+      label="Delayable requests in-flight were counted. Recorded only if
+             there is at least one layout blocking request in-flight."/>
+  <suffix name="DelayableWhenNonDelayable"
+      label="Delayable requests in-flight were counted. Recorded only if
+             there is at least one non-delayable blocking request in-flight."/>
+  <affected-histogram name="ResourceScheduler.RequestsCount"/>
+</histogram_suffixes>
+
 <histogram_suffixes name="ResourceType" separator=".">
   <suffix name="MainResource"/>
   <suffix name="Image"/>