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

chrome/browser/page_load_metrics/observers/page_load_metrics_observers_unittest.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 "base/memory/scoped_ptr.h"
 #include "base/test/histogram_tester.h"
 #include "chrome/browser/page_load_metrics/observers/from_gws_page_load_metrics_observer.h"
+#include "chrome/browser/page_load_metrics/observers/google_captcha_observer.h"
 #include "chrome/test/base/chrome_render_view_host_test_harness.h"
 #include "components/page_load_metrics/browser/metrics_web_contents_observer.h"
 #include "components/page_load_metrics/common/page_load_metrics_messages.h"
 #include "content/public/test/web_contents_tester.h"
 #include "url/gurl.h"
 
 namespace {
 
 const char kHistogramNameFromGWSFirstTextPaint[] =
     "PageLoad.Clients.FromGWS.Timing2.NavigationToFirstTextPaint";
@@ skipping 171 matching lines @@
       GURL("https://www.anothersite.com"), blink::WebReferrerPolicyDefault));
 
   observer_->OnMessageReceived(
       PageLoadMetricsMsg_TimingUpdated(observer_->routing_id(), timing),
       web_contents()->GetMainFrame());
 
   // Navigate again to force logging.
   NavigateAndCommit(GURL("https://www.google.com"));
   histogram_tester_.ExpectTotalCount(kHistogramNameFromGWSFirstTextPaint, 0);
 }
+
+TEST_F(PageLoadMetricsObserverTest, IsGoogleCaptcha) {

[Randy Smith (Not in Mondays), 2015/11/14 01:45:48]

Charles: Did we have a conversation about all the different observers sharing a
file for the unittests?  It seems weird to me to have the actual code broken out
into a separate file and the test code shared.

+  struct {
+    std::string url;
+    bool expected;
+  } test_cases[] = {
+      {"", false},
+      {"http://www.google.com/", false},
+      {"http://www.cnn.com/", false},
+      {"http://ipv4.google.com/", false},
+      {"https://ipv4.google.com/sorry/IndexRedirect?continue=http://a", true},
+      {"https://ipv6.google.com/sorry/IndexRedirect?continue=http://a", true},
+      {"https://ipv7.google.com/sorry/IndexRedirect?continue=http://a", false},
+  };
+  for (const auto& test : test_cases) {
+    EXPECT_EQ(test.expected,
+              google_captcha_observer::IsGoogleCaptcha(GURL(test.url)))
+        << "for URL: " << test.url;
+  }
+}