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

components/page_load_metrics/browser/metrics_web_contents_observer.cc

Index: components/page_load_metrics/browser/metrics_web_contents_observer.cc
diff --git a/components/page_load_metrics/browser/metrics_web_contents_observer.cc b/components/page_load_metrics/browser/metrics_web_contents_observer.cc
index c8bd56ac526e7eb390799443b470c1957289b9f3..f8040d4043ae2dfdeb3ed9a649423c08c509574b 100644
--- a/components/page_load_metrics/browser/metrics_web_contents_observer.cc
+++ b/components/page_load_metrics/browser/metrics_web_contents_observer.cc
@@ -7,6 +7,7 @@
 #include "base/location.h"
 #include "base/logging.h"
 #include "base/metrics/histogram.h"
+#include "base/metrics/user_metrics.h"
 #include "components/page_load_metrics/browser/page_load_metrics_macros.h"
 #include "components/page_load_metrics/common/page_load_metrics_messages.h"
 #include "components/page_load_metrics/common/page_load_timing.h"
@@ -27,6 +28,9 @@ DEFINE_WEB_CONTENTS_USER_DATA_KEY(
 
 namespace page_load_metrics {
 
+const char kUMAGoogleCaptchaHistogram[] =
+  "GoogleCaptcha.Event";
+
 namespace {
 
 // The url we see from the renderer side is not always the same as what
@@ -119,6 +123,14 @@ uint64_t RapporHistogramBucketIndex(const base::TimeDelta& time) {
 
 }  // namespace
 
+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);
+}
+
 PageLoadTracker::PageLoadTracker(
     bool in_foreground,
     rappor::RapporService* const rappor_service,
@@ -439,6 +451,11 @@ void MetricsWebContentsObserver::DidStartNavigation(
 
 void MetricsWebContentsObserver::DidFinishNavigation(
     content::NavigationHandle* navigation_handle) {
+  if (IsGoogleCaptcha(navigation_handle->GetURL())) {
+    UMA_HISTOGRAM_ENUMERATION(kUMAGoogleCaptchaHistogram, GOOGLE_CAPTCHA_SHOWN,

[Alexei Svitkine (slow), 2015/11/13 19:41:57]

Nit: Can you make a helper function to log this histogram? Each macro expands to
quite a bit of code, so having a helper function avoids some bloat. Then, you
can just inline the histogram name in the macro instead of a separate constant.

[Matt Welsh, 2015/11/13 20:15:19]

Done.

+                              GOOGLE_CAPTCHA_EVENT_BOUNDARY);
+  }
+
   if (!navigation_handle->IsInMainFrame())
     return;
 
@@ -481,6 +498,14 @@ void MetricsWebContentsObserver::DidFinishNavigation(
   committed_load_->Commit(navigation_handle);
 }
 
+void MetricsWebContentsObserver::DidRedirectNavigation(
+    content::NavigationHandle* navigation_handle) {
+  if (IsGoogleCaptcha(navigation_handle->GetReferrer().url)) {
+    UMA_HISTOGRAM_ENUMERATION(kUMAGoogleCaptchaHistogram, GOOGLE_CAPTCHA_SOLVED,
+                              GOOGLE_CAPTCHA_EVENT_BOUNDARY);
+  }
+}
+
 void MetricsWebContentsObserver::WasShown() {
   in_foreground_ = true;
   if (committed_load_)