NTP: add histogram to track New Tab page URL status.

chrome/browser/search/search.cc

 // Copyright 2012 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/search/search.h"
 
 #include "base/command_line.h"
 #include "base/metrics/field_trial.h"
+#include "base/metrics/histogram.h"
 #include "base/prefs/pref_service.h"
 #include "base/strings/string_number_conversions.h"
 #include "base/strings/string_split.h"
 #include "base/strings/utf_string_conversions.h"
 #include "chrome/browser/browser_process.h"
 #include "chrome/browser/google/google_util.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/browser/profiles/profile_manager.h"
 #include "chrome/browser/search/instant_service.h"
 #include "chrome/browser/search/instant_service_factory.h"
@@ skipping 60 matching lines @@
 // Dev & Canary, for now the code accepts both names.
 // TODO(dcblack): Remove the InstantExtended name once M31 hits the Beta
 // channel.
 const char kInstantExtendedFieldTrialName[] = "InstantExtended";
 const char kEmbeddedSearchFieldTrialName[] = "EmbeddedSearch";
 
 // If the field trial's group name ends with this string its configuration will
 // be ignored and Instant Extended will not be enabled by default.
 const char kDisablingSuffix[] = "DISABLED";
 
+// Reasons for falling back to the local NTP instead of using a valid search
+// provider's URL.

[Alexei Svitkine (slow), 2014/01/30 15:19:24]

Mention that this is used in an UMA macro, so new values should be added at the
end and existing values shouldn't be re-ordered or removed.

[samarth, 2014/01/30 16:45:29]

Done.

+enum LocalNTPFallbackReason {
+  LOCAL_NTP_FALLBACK_INSECURE_URL = 1,
+  LOCAL_NTP_FALLBACK_SUGGEST_OFF = 2,
+  LOCAL_NTP_FALLBACK_BLOCKED_URL = 3,
+  LOCAL_NTP_FALLBACK_MAX = 4

[Alexei Svitkine (slow), 2014/01/30 15:19:24]

Maybe better to remove the = 4 here, so that it automatically is set to the last
value + 1 (so that new values being added don't need to update it).

[samarth, 2014/01/30 16:45:29]

Done.

+};
+
 // Used to set the Instant support state of the Navigation entry.
 const char kInstantSupportStateKey[] = "instant_support_state";
 
 const char kInstantSupportEnabled[] = "Instant support enabled";
 const char kInstantSupportDisabled[] = "Instant support disabled";
 const char kInstantSupportUnknown[] = "Instant support unknown";
 
 InstantSupportState StringToInstantSupportState(const base::string16& value) {
   if (value == base::ASCIIToUTF16(kInstantSupportEnabled))
     return INSTANT_SUPPORT_YES;
@@ skipping 348 matching lines @@
     result.push_back(TemplateURLRefToGURL(ref, kDisableStartMargin, false,
                                           false));
   }
   return result;
 }
 
 GURL GetNewTabPageURL(Profile* profile) {
   if (!profile || profile->IsOffTheRecord())
     return GURL();
 
-  if (!IsSuggestPrefEnabled(profile))
-    return GURL(chrome::kChromeSearchLocalNtpUrl);
-
   TemplateURL* template_url = GetDefaultSearchProviderTemplateURL(profile);
   if (!template_url)
     return GURL(chrome::kChromeSearchLocalNtpUrl);
 
   GURL url(TemplateURLRefToGURL(template_url->new_tab_url_ref(),
                                 kDisableStartMargin, false, false));
-  if (!url.is_valid() || !url.SchemeIsSecure())
+  if (!url.is_valid())
     return GURL(chrome::kChromeSearchLocalNtpUrl);
 
-  if (!IsURLAllowedForSupervisedUser(url, profile))
+  if (!url.SchemeIsSecure()) {
+    UMA_HISTOGRAM_ENUMERATION("InstantExtended.LocalNTPFallbackReason",

[Alexei Svitkine (slow), 2014/01/30 15:19:24]

Can you make a small helper function in the anon namespace that wraps this macro
and takes just the enum value? That way, you don't need to repeat the string and
it's more efficient from code size perspective (the macro expands to a blob of
code, so having it in a single place avoids the duplication.)

[samarth, 2014/01/30 16:45:29]

Done.

+                              LOCAL_NTP_FALLBACK_INSECURE_URL,
+                              LOCAL_NTP_FALLBACK_MAX);
     return GURL(chrome::kChromeSearchLocalNtpUrl);
+  }
+
+  if (!IsSuggestPrefEnabled(profile)) {
+    UMA_HISTOGRAM_ENUMERATION("InstantExtended.LocalNTPFallbackReason",
+                              LOCAL_NTP_FALLBACK_SUGGEST_OFF,
+                              LOCAL_NTP_FALLBACK_MAX);
+    return GURL(chrome::kChromeSearchLocalNtpUrl);
+  }
+
+  if (!IsURLAllowedForSupervisedUser(url, profile)) {
+    UMA_HISTOGRAM_ENUMERATION("InstantExtended.LocalNTPFallbackReason",
+                              LOCAL_NTP_FALLBACK_BLOCKED_URL,
+                              LOCAL_NTP_FALLBACK_MAX);
+    return GURL(chrome::kChromeSearchLocalNtpUrl);
+  }
 
   return url;
 }
 
 GURL GetSearchResultPrefetchBaseURL(Profile* profile) {
   return ShouldPrefetchSearchResults() ?
       GetInstantURL(profile, kDisableStartMargin, true) : GURL();
 }
 
 bool ShouldPrefetchSearchResults() {
@@ skipping 222 matching lines @@
 
 // Given a FieldTrialFlags object, returns the boolean value of the provided
 // flag.
 bool GetBoolValueForFlagWithDefault(const std::string& flag,
                                     bool default_value,
                                     const FieldTrialFlags& flags) {
   return !!GetUInt64ValueForFlagWithDefault(flag, default_value ? 1 : 0, flags);
 }
 
 }  // namespace chrome