Add metrics to printer setup flow.

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 5f4ea6b4c6d4365f4b0633e3bf7e3d02fdd9071e..15a35b0a93ef5eb9b36e6f60ab8559d05f7106f0 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -57069,6 +57069,24 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   </summary>
 </histogram>
 
+<histogram name="Printing.CUPS.PpdSource" enum="PpdSource">
+  <owner>skau@chromium.org</owner>
+  <summary>
+    Records the source of PostScript Printer Description files used during
+    printer setup.  Entries are recorded for every attempted configuration. Only
+    recorded on Chrome OS.
+  </summary>
+</histogram>
+
+<histogram name="Printing.CUPS.PrinterSetupResult" enum="PrinterSetupResult">
+  <owner>skau@chromium.org</owner>
+  <summary>
+    The success or error code for the set up of a CUPS printer.  Recorded when

[michaelpg, 2017/05/30 21:14:48]

nit: setup, x2

[skau, 2017/05/30 22:17:08]

Done.

+    set up is attempted through the settings dialogs.  Only recorded on Chrome
+    OS.
+  </summary>
+</histogram>
+
 <histogram name="Printing.CUPS.PrintJobsQueued" units="count">
   <owner>skau@chromium.org</owner>
   <summary>