Setting chrome as the default browser is now fixed on Windows 10

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 0116bbedb3bb88baf7997c1803f64c528c4fbb37..23665c9fd6aba6969eaa60dbeeb3e66edf8f15d1 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -1810,6 +1810,22 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   </summary>
 </histogram>
 
+<histogram name="AsyncSetAsDefault.Duration" units="milliseconds">

[Alexei Svitkine (slow), 2015/09/22 15:20:43]

The AsyncSetAsDefault top-level prefix doesn't sound very meaningful to me.
Suggest nesting things under the existing DefaultBrowser.* prefix.

[Patrick Monette, 2015/09/22 17:11:09]

Done.

+  <owner>pmonette@chromium.org</owner>
+  <summary>
+    How long it took to set Chrome as the default browser asynchronously in
+    Windows 10+.
+  </summary>
+</histogram>
+
+<histogram name="AsyncSetAsDefault.Success">
+  <owner>pmonette@chromium.org</owner>
+  <summary>
+    The count of how many times users were successfully able to set Chrome as
+    the default browser asynchronously in Windows 10+.
+  </summary>
+</histogram>
+
 <histogram name="Aura.CreatedGpuBrowserCompositor" enum="CompositorType">
   <owner>jbauman@chromium.org</owner>
   <summary>