Omnibox: In UMA logs, record typed_count of URLS.

chrome/common/metrics/proto/omnibox_event.proto

Index: chrome/common/metrics/proto/omnibox_event.proto
diff --git a/chrome/common/metrics/proto/omnibox_event.proto b/chrome/common/metrics/proto/omnibox_event.proto
index a46c2874e3d6d7277f5d7b66a40a9ab8313a5e84..2c2bc9967a01559f4a2d8970639c7680b8442ebd 100644
--- a/chrome/common/metrics/proto/omnibox_event.proto
+++ b/chrome/common/metrics/proto/omnibox_event.proto
@@ -88,6 +88,7 @@ message OmniboxEventProto {
   }
 
   // The result set displayed on the completion popup
+  // Next tag: 6
   message Suggestion {
     // Where does this result come from?
     optional ProviderType provider = 1;
@@ -119,6 +120,12 @@ message OmniboxEventProto {
     // The relevance score for this suggestion.
     optional int32 relevance = 3;
 
+    // How many times this result was typed in / selected from the omnibox.
+    // Only set for some providers and result_types.  At the time of
+    // writing this comment, it is only set for HistoryURL and
+    // HistoryQuickProvider matches.
+    optional int32 typed_count = 5;
+
     // Whether this item is starred (bookmarked) or not.
     optional bool is_starred = 4;
   }