Add memory and CPU histogram for OOPIF

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 0e344eb8b5f4cb5a41835ed181b3841e832e788c..edf7fc63c3ce8422ab3919d827b3df6b1636f6ee 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -64495,6 +64495,33 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   </summary>
 </histogram>
 
+<histogram name="SiteIsolation.Oopif.AverageCPU" units="PercentCPUUsage">
+  <owner>apisarev@yandex-team.ru</owner>
+  <summary>
+    Average CPU utilization of a out-of-process iframe renderer process, read
+    out at each two-minute interval. The utilization is in the 0-100% range per
+    CPU, which is then summed up. I.e. a quadcore system fully loaded would read
+    as 400%.
+  </summary>
+</histogram>
+
+<histogram name="SiteIsolation.Oopif.HighCPU" enum="BooleanHit">
+  <owner>apisarev@yandex-team.ru</owner>
+  <summary>
+    The number of times a out-of-process iframe renderer process has
+    continuously stayed above a certain threshold of CPU utilization over a
+    certain time period (currently set to two minutes).
+  </summary>
+</histogram>
+
+<histogram name="SiteIsolation.Oopif.Memory" units="KB">
+  <owner>apisarev@yandex-team.ru</owner>
+  <summary>
+    The private working set used by each out-of-process iframe renderer process.
+    Each process provides one sample.  Recorded once per UMA ping.
+  </summary>
+</histogram>
+
 <histogram name="SiteIsolation.OutOfProcessIframes">
   <owner>nasko@chromium.org</owner>
   <summary>