Add installer metrics for operations on the archive.

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 ca6b8c62374959355279357142603ea2a58786d2..017c50e88998edd101aa04358f740be3d1cd8042 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -46247,6 +46247,48 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   </summary>
 </histogram>
 
+<histogram name="Setup.Install.ApplyArchivePathTime" units="ms">

[bcwhite, 2016/02/25 16:46:50]

Patch

[grt (UTC plus 2), 2016/02/25 17:45:26]

Done.

+  <owner>grt@chromium.org</owner>
+  <summary>
+    The elapesed time to apply a patch to a previous version's chrome.7z archive
+    to generate a new chrome.7z archive. This histogram only applies to diff
+    updates.
+  </summary>
+</histogram>
+
+<histogram name="Setup.Install.HasArchivePatch" enum="Boolean">
+  <owner>grt@chromium.org</owner>
+  <summary>
+    True if the chrome.packed.7z archive contains a patch (in which case a diff
+    update is taking place), or false if it contains a full archive (in which

[bcwhite, 2016/02/25 16:46:50]

No comma.

[grt (UTC plus 2), 2016/02/25 17:45:26]

Done.

+    case a new install or a full update is taking place).
+  </summary>
+</histogram>
+
+<histogram name="Setup.Install.UncompressArchivePatchTime" units="ms">
+  <owner>grt@chromium.org</owner>
+  <summary>
+    The elapsed time to uncompress a chrome.7z patch. This histogram only
+    applies to diff updates.
+  </summary>
+</histogram>
+
+<histogram name="Setup.Install.UncompressFullArchiveTime" units="ms">
+  <owner>grt@chromium.org</owner>
+  <summary>
+    The elapsed time to uncompress a full chrome.7z archive. This histogram only
+    applies to new installs and to full updates.
+  </summary>
+</histogram>
+
+<histogram name="Setup.Install.UnpackFullArchiveTime" units="ms">
+  <owner>grt@chromium.org</owner>
+  <summary>
+    The elapsed time to unpack the uncompressed chrome.7z archive. This
+    histogram applies to all installs and updates.
+  </summary>
+</histogram>
+
 <histogram name="SharedMemory.TimeSpentMakingAnonymousMemory" units="ms">
   <obsolete>
     Deprecated 2015-06 because the Finch experiment SharedMemoryCreateStrategy