Stability instrumentation: metrics for collection on crash

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 6ed192b3a430a9c42cd098e58111a7082c27aa59..b990609f1b4ccec7c33886d37d5b70cf864e0f79 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -449,13 +449,12 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   </summary>
 </histogram>
 
-<histogram name="ActivityTracker.CollectCrash.OpenForDeleteSuccess"
-    enum="BooleanSuccess">
+<histogram name="ActivityTracker.CollectCrash.CrashCount"
+    units="count">
   <owner>manzagop@chromium.org</owner>
   <summary>
-    Success of the attempt to open the debug file for deletion. Logged each time
-    a debug file is opened for deletion during collection from the crash
-    handler.
+    Number of times the stability instrumentation is successfully collected on
+    crash. Logged on crash collection, if the collection is successful.
   </summary>
 </histogram>
 
@@ -477,6 +476,16 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   </summary>
 </histogram>
 
+<histogram name="ActivityTracker.Record.SetPmaDeletedSuccess"
+    enum="BooleanSuccess">
+  <owner>manzagop@chromium.org</owner>
+  <summary>
+    Success of the attempt to open the debug file and set its persistent memory
+    allocator state to deleted. Logged each time a debug file from a different
+    process is marked as deleted.
+  </summary>
+</histogram>
+
 <histogram name="ActivityTracker.Record.SetupTime" units="ms">
   <owner>manzagop@chromium.org</owner>
   <summary>