Add UMA to count the number of Google CAPTCHA pages shown and solved by users.

chrome/browser/page_load_metrics/observers/google_captcha_observer.cc

+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "chrome/browser/page_load_metrics/observers/google_captcha_observer.h"
+
+#include "base/metrics/histogram.h"
+#include "base/strings/string_util.h"
+#include "components/page_load_metrics/browser/page_load_metrics_macros.h"
+#include "components/page_load_metrics/common/page_load_timing.h"
+#include "net/base/registry_controlled_domains/registry_controlled_domain.h"
+
+namespace {

[Charlie Harrison, 2015/11/14 01:19:55]

Nest the anonymous namespace within the google_captcha_observer namespace.

[Matt Welsh, 2015/11/16 18:30:53]

Done.

+
+const char kHistogramNameGoogleCaptcha[] = "PageLoad.Events.GoogleCaptcha";

[Charlie Harrison, 2015/11/14 01:19:55]

Can you follow the same naming style as other histogram clients? Look at FromGWS
as an example. Here it should be "PageLoad.Clients.GoogleCaptcha.Events"

This was originally meant to be as a histogram prefix, but I think it makes
sense to overload the name for client specific events. 

Also, change the name to something like "kGoogleCaptchaEvents," to be more in
line with constant redefinition in this pending CL:
https://codereview.chromium.org/1417733011/

[Matt Welsh, 2015/11/16 18:30:53]

Done.

+
+void RecordGoogleCaptchaEvent(
+    google_captcha_observer::GoogleCaptchaEvent event) {
+  UMA_HISTOGRAM_ENUMERATION(
+      kHistogramNameGoogleCaptcha, event,
+      google_captcha_observer::GOOGLE_CAPTCHA_EVENT_BOUNDARY);
+}
+
+} // namespace
+
+namespace google_captcha_observer {
+
+bool IsGoogleCaptcha(const GURL& url) {
+  return (base::StartsWith(url.host(), "ipv4.google.",
+                           base::CompareCase::SENSITIVE)
+          || base::StartsWith(url.host(), "ipv6.google.",
+                              base::CompareCase::SENSITIVE))
+      && base::StartsWith(url.path(), "/sorry", base::CompareCase::SENSITIVE);
+}
+
+GoogleCaptchaObserver::GoogleCaptchaObserver(
+    page_load_metrics::PageLoadMetricsObservable* metrics)
+ : metrics_(metrics) {}
+
+void GoogleCaptchaObserver::OnCommit(
+    content::NavigationHandle* navigation_handle) {
+  if (IsGoogleCaptcha(navigation_handle->GetURL()))
+    RecordGoogleCaptchaEvent(GOOGLE_CAPTCHA_SHOWN);
+}
+
+void GoogleCaptchaObserver::OnRedirect(
+    content::NavigationHandle* navigation_handle) {
+  if (navigation_handle->GetReferrer() &&
+      IsGoogleCaptcha(navigation_handle->GetReferrer().url))
+    RecordGoogleCaptchaEvent(GOOGLE_CAPTCHA_SOLVED);
+}
+
+void GoogleCaptchaObserver::OnPageLoadMetricsGoingAway() {
+  metrics_->RemoveObserver(this);
+  delete this;
+}
+
+} // namespace google_captcha_observer

[Charlie Harrison, 2015/11/14 01:19:55]

nit: two spaces between } and // (ditto other places where this occurs)

[Matt Welsh, 2015/11/16 18:30:53]

Done. How do I autoformat my code to adhere to Chromium style?

[Charlie Harrison, 2015/11/16 19:12:38]

"git cl format" should do it. See
https://code.google.com/p/chromium/codesearch#chromium/src/docs/clang_format....