Add UMA for window.external.AddSearchProvider (Chrome side).

chrome/browser/ui/search_engines/edit_search_engine_controller.cc

Index: chrome/browser/ui/search_engines/edit_search_engine_controller.cc
diff --git a/chrome/browser/ui/search_engines/edit_search_engine_controller.cc b/chrome/browser/ui/search_engines/edit_search_engine_controller.cc
index 126af58d01afe94b70b0d82bd18ca0fcf0126a9c..8d974cc8b89fb641d736059e078a44364a922181 100644
--- a/chrome/browser/ui/search_engines/edit_search_engine_controller.cc
+++ b/chrome/browser/ui/search_engines/edit_search_engine_controller.cc
@@ -4,6 +4,7 @@
 
 #include "chrome/browser/ui/search_engines/edit_search_engine_controller.h"
 
+#include "base/metrics/histogram_macros.h"
 #include "base/strings/string_util.h"
 #include "base/strings/utf_string_conversions.h"
 #include "chrome/browser/profiles/profile.h"
@@ -24,6 +25,9 @@ EditSearchEngineController::EditSearchEngineController(
       edit_keyword_delegate_(edit_keyword_delegate),
       profile_(profile) {
   DCHECK(profile_);
+  UMA_HISTOGRAM_ENUMERATION("Search.AddSearchProvider",
+                            CONFIRMATION_DIALOG_SHOWN,
+                            NUM_EDIT_SEARCH_ENGINE_ACTIONS);
 }
 
 bool EditSearchEngineController::IsTitleValid(
@@ -112,6 +116,10 @@ void EditSearchEngineController::AcceptAddOrEdit(
     edit_keyword_delegate_->OnEditedKeyword(template_url_, title_input,
                                             keyword_input, url_string);
   }
+
+  UMA_HISTOGRAM_ENUMERATION("Search.AddSearchProvider",
+                            CONFIRMATION_DIALOG_CONFIRMED,
+                            NUM_EDIT_SEARCH_ENGINE_ACTIONS);
 }
 
 void EditSearchEngineController::CleanUpCancelledAdd() {
@@ -121,6 +129,10 @@ void EditSearchEngineController::CleanUpCancelledAdd() {
     delete template_url_;
     template_url_ = NULL;
   }
+
+  UMA_HISTOGRAM_ENUMERATION("Search.AddSearchProvider",
+                            CONFIRMATION_DIALOG_CANCELLED,
+                            NUM_EDIT_SEARCH_ENGINE_ACTIONS);
 }
 
 std::string EditSearchEngineController::GetFixedUpURL(