Log the creation of dialog boxes using DialogDelegateView and BubbleDialogDelegateView.

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 425d72eb20bd0ecc6a4649145e64a0c03d674363..375d9e179cf1fa72a7da47447d23e39ffa8b5024 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -11909,6 +11909,14 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   </summary>
 </histogram>
 
+<histogram name="Dialog.Create" enum="BooleanCreated">
+  <owner>pdyson@chromium.org</owner>
+  <summary>
+    Counts the number times dialog boxes are created using a particular parent
+    class.
+  </summary>
+</histogram>
+
 <histogram name="Dialog.Creation" enum="DialogName">
   <owner>pdyson@chromium.org</owner>
   <summary>
@@ -85389,6 +85397,18 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   <affected-histogram name="DesktopIOSPromotion.VariationSigninReason"/>
 </histogram_suffixes>
 
+<histogram_suffixes name="DialogTypes" separator="." ordering="prefix">
+  <suffix name="DialogDelegateView"
+      label="Counts dialog boxes created using DialogDelegateView. These are
+             a subset of those created with DialogDelegate."/>
+  <suffix name="BubbleDialogDelegateView"
+      label="Counts dialog boxes created using BubbleDialogDelegateView.
+             These are a subset of those created with DialogDelegateView
+             (which, in turn, are a subset of those created with
+             DialogDelegate)."/>
+  <affected-histogram name="Dialog.Create"/>
+</histogram_suffixes>
+
 <histogram_suffixes name="DiskUsagePerUserCount" separator=".">
   <suffix name="1User" label="Only 1 user exists on device."/>
   <suffix name="2Users" label="2 users exist on device."/>