Log to UMA why we would load a third-party frame

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 cdbc1e03a7b539b67c5c89433caa24dc467f0024..36431416d8b9ed9f9cd76fc50456907f88b1e014 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -27399,6 +27399,9 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
 
 <histogram name="Navigation.DeferredDocumentLoading.StatesV1"
     enum="DocumentStateForDeferredLoading">
+  <obsolete>
+    Deprecated 10/2016 in favor of Navigation.DeferredDocumentLoading.StatesV2.
+  </obsolete>
   <owner>dgrogan@chromium.org</owner>
   <summary>
     Why and if cross-origin documents would be loaded in a world where we defer
@@ -27406,6 +27409,15 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   </summary>
 </histogram>
 
+<histogram name="Navigation.DeferredDocumentLoading.StatesV2"
+    enum="DocumentStateForDeferredLoadingV2">
+  <owner>dgrogan@chromium.org</owner>
+  <summary>
+    Why and if cross-origin documents would be loaded if we were to defer
+    loading as long as possible.
+  </summary>
+</histogram>
+
 <histogram name="Navigation.EngagementTime.HTTP" units="ms">
   <owner>felt@chromium.org</owner>
   <summary>
@@ -78325,6 +78337,16 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   <int value="1" label="WouldLoadBecauseVisible"/>
 </enum>
 
+<enum name="DocumentStateForDeferredLoadingV2" type="int">
+  <int value="0" label="Created"/>
+  <int value="1" label="WouldLoadOutOfProcess"/>
+  <int value="2" label="WouldLoadDisplayNone"/>
+  <int value="3" label="WouldLoadZeroByZero"/>
+  <int value="4" label="WouldLoadAbove"/>
+  <int value="5" label="WouldLoadLeft"/>
+  <int value="6" label="WouldLoadVisible"/>
+</enum>
+
 <enum name="DocumentWriteGatedEvaluation" type="int">
   <int value="0" label="Script too long"/>
   <int value="1" label="No likely external script write"/>