Support --delete-old-versions in setup.exe.

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 752b6131947870e3170b0851340c0b75c0858cfb..03a0f09234ca5c7571e2ed99208bb859aa8c0381 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -55917,6 +55917,34 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   </summary>
 </histogram>
 
+<histogram name="Setup.Install.NumDeleteOldVersionsAttemptsBeforeAbort"
+    units="Attempts">
+  <owner>fdoray@chromium.org</owner>
+  <summary>
+    Number of calls to DeleteOldVerions() made by a --delete-old-versions
+    process that didn't delete all files that belong to old versions of Chrome.
+    A --delete-old-versions process exits when another process tries to acquire
+    the SetupSingleton or after too many unsuccessful attempts to delete all old
+    files. A --delete-old-versions process that successfully acquires the
+    SetupSingleton records to either the
+    Setup.Install.NumDeleteOldVersionsAttemptsBeforeAbort histogram or the
+    Setup.Install.NumDeleteOldVersionsAttemptsBeforeSuccess histogram.
+  </summary>
+</histogram>
+
+<histogram name="Setup.Install.NumDeleteOldVersionsAttemptsBeforeSuccess"
+    units="Attempts">
+  <owner>fdoray@chromium.org</owner>
+  <summary>
+    Number of calls to DeleteOldVersions() made by a --delete-old-versions
+    process that successfully deleted all files that belong to old versions of
+    Chrome. A --delete-old-versions process that successfully acquires the
+    SetupSingleton records to either the
+    Setup.Install.NumDeleteOldVersionsAttemptsBeforeAbort histogram or the
+    Setup.Install.NumDeleteOldVersionsAttemptsBeforeSuccess histogram.
+  </summary>
+</histogram>
+
 <histogram name="Setup.Install.PeakPagefileUsage" units="KB">
   <owner>huangs@chromium.org</owner>
   <summary>
@@ -85549,6 +85577,9 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   <int value="58" label="IN_USE_DOWNGRADE"/>
   <int value="59" label="OLD_VERSION_DOWNGRADE"/>
   <int value="60" label="SETUP_SINGLETON_ACQUISITION_FAILED"/>
+  <int value="61" label="SETUP_SINGLETON_RELEASED"/>
+  <int value="62" label="DELETE_OLD_VERSIONS_SUCCESS"/>
+  <int value="63" label="DELETE_OLD_VERSIONS_TOO_MANY_ATTEMPTS"/>
 </enum>
 
 <enum name="InstantControllerEvent" type="int">