Add a histogram for each time the HTTP Bad UI is shown

chrome/browser/ssl/chrome_security_state_model_client.cc

Index: chrome/browser/ssl/chrome_security_state_model_client.cc
diff --git a/chrome/browser/ssl/chrome_security_state_model_client.cc b/chrome/browser/ssl/chrome_security_state_model_client.cc
index 5b7097e4b4e89c8b0c8ad8d31ffc030aa4cd8fbe..383a5c9cbf913f024e2eaf751973d9b915b14a7f 100644
--- a/chrome/browser/ssl/chrome_security_state_model_client.cc
+++ b/chrome/browser/ssl/chrome_security_state_model_client.cc
@@ -344,12 +344,17 @@ void ChromeSecurityStateModelClient::VisibleSSLStateChanged() {
           "This page includes a password or credit card input in a non-secure "
           "context. A warning has been added to the URL bar. For more "
           "information, see https://goo.gl/zmWq3m.";
+      UMA_HISTOGRAM_BOOLEAN("Security.HTTPBad.UserWarnedAboutSensitiveInput",

[estark, 2016/10/26 20:30:56]

I'm not 100% sure, but I think, because of
https://cs.chromium.org/chromium/src/base/metrics/histogram_macros.h?q=UMA_HI...,
you're not supposed to use different strings to record the same histogram? When
you add a histograms.xml owner they'll tell you for sure.

It might be simpler in any case to do:

bool histogram_sample = false;
switch (security_info.security_level) {
// set histogram_sample in here
}
UMA_HISTOGRAM_BOOLEAN("Security.HTTPBad.UserWarnedAboutSensitiveInput",
histogram_sample);

+                            true);
       break;
     case security_state::SecurityStateModel::NONE:
+    case security_state::SecurityStateModel::DANGEROUS:
       warning =
           "This page includes a password or credit card input in a non-secure "
           "context. A warning will be added to the URL bar in Chrome 56 (Jan "
           "2017). For more information, see https://goo.gl/zmWq3m.";
+      UMA_HISTOGRAM_BOOLEAN("Security.HTTPBad.UserWarnedAboutSensitiveInput",
+                            false);
       break;
     default:
       return;