Add UMA metrics regarding default browser status

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 c5a6a1051d3ab145f47801f6850103b3fd4ca7ec..c843275ccb0c9cd8397a90d2bf83ffeee13db16e 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -30483,6 +30483,21 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   </summary>
 </histogram>
 
+<histogram name="Mobile.DefaultBrowser.BrowserCount">
+<!-- Name completed by histogram_suffixes name="Mobile.DefaultBrowser.Type" -->
+
+  <owner>dtrainor@chromium.org</owner>
+  <summary>Android: The number of browsers installed on the device.</summary>
+</histogram>
+
+<histogram name="Mobile.DefaultBrowser.State" enum="MobileDefaultBrowserState">
+  <owner>dtrainor@chromium.org</owner>
+  <summary>
+    Android: Whether or not the device has a default browser and whether or not
+    it is a system installed browser.
+  </summary>
+</histogram>
+
 <histogram name="Mobile.SystemNotification.Blocked"
     enum="SystemNotificationType">
   <owner>dtrainor@chromium.org</owner>
@@ -106080,6 +106095,14 @@ from previous Chrome versions.
   <int value="1" label="Failure"/>
 </enum>
 
+<enum name="MobileDefaultBrowserState" type="int">
+  <int value="0" label="No default"/>
+  <int value="1" label="Chrome: System default"/>
+  <int value="2" label="Chrome: Installed default"/>
+  <int value="3" label="Other: System default"/>
+  <int value="4" label="Other: Installed default"/>
+</enum>
+
 <enum name="MobileDownloadCancelReason" type="int">
   <int value="0" label="Not canceled"/>
   <int value="1" label="Click on the cancel button"/>
@@ -122716,6 +122739,13 @@ from previous Chrome versions.
   <affected-histogram name="Memory.Coordinator.TotalPrivate"/>
 </histogram_suffixes>
 
+<histogram_suffixes name="Mobile.DefaultBrowser.Type" separator=".">
+  <suffix name="ChromeDefault" label="Chrome is the default browser."/>
+  <suffix name="NoDefault" label="There is no default browser."/>
+  <suffix name="OtherDefault" label="Another browser is the default browser."/>
+  <affected-histogram name="Mobile.DefaultBrowser.BrowserCount"/>
+</histogram_suffixes>
+
 <histogram_suffixes name="MobileDownloadBytesDownloadedTypes" separator=".">
   <suffix name="ChromeNetworkStack.Failure"/>
   <suffix name="ChromeNetworkStack.Success"/>