Add a counter for clicking on Form-Not-Secure warnings

chrome/browser/ui/autofill/chrome_autofill_client.cc

Index: chrome/browser/ui/autofill/chrome_autofill_client.cc
diff --git a/chrome/browser/ui/autofill/chrome_autofill_client.cc b/chrome/browser/ui/autofill/chrome_autofill_client.cc
index 613753281d8638884e2b1fc25b14c55d6e0b3f02..4a1c170d5fea0d25336be30554e9a21f63ffb545 100644
--- a/chrome/browser/ui/autofill/chrome_autofill_client.cc
+++ b/chrome/browser/ui/autofill/chrome_autofill_client.cc
@@ -10,6 +10,7 @@
 #include "base/command_line.h"
 #include "base/logging.h"
 #include "base/memory/ptr_util.h"
+#include "base/metrics/histogram_macros.h"
 #include "build/build_config.h"
 #include "chrome/browser/autofill/personal_data_manager_factory.h"
 #include "chrome/browser/autofill/risk_util.h"
@@ -378,6 +379,7 @@ void ChromeAutofillClient::StartSigninFlow() {
 }
 
 void ChromeAutofillClient::ShowHttpNotSecureExplanation() {
+  UMA_HISTOGRAM_BOOLEAN("Autofill.ShowHttpNotSecureExplanation", true);

[Mathieu, 2017/02/01 13:45:39]

consider using a user action:
https://cs.chromium.org/chromium/src/components/autofill/core/browser/autofil...

Also, create a function in autofill_metrics and call it from here.

[estark, 2017/02/01 18:55:49]

Oh I've always wondered why something like that doesn't exist, TIL! Thanks!
Done.

 #if !defined(OS_ANDROID)
   // On desktop platforms, open Page Info, which briefly explains the HTTP
   // warning message and provides a link to the Help Center for more details.