Settings reset prompt: add UMA metrics reporting.

chrome/browser/safe_browsing/settings_reset_prompt/settings_reset_prompt_model.cc

 // Copyright 2017 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/safe_browsing/settings_reset_prompt/settings_reset_prompt_model.h"
 
 #include <utility>
 
 #include "base/bind_helpers.h"
 #include "base/callback.h"
+#include "base/metrics/histogram_macros.h"
 #include "chrome/browser/extensions/extension_service.h"
 #include "chrome/browser/google/google_brand.h"
 #include "chrome/browser/prefs/session_startup_pref.h"
 #include "chrome/browser/profile_resetter/brandcode_config_fetcher.h"
 #include "chrome/browser/profile_resetter/brandcoded_default_settings.h"
 #include "chrome/browser/profile_resetter/resettable_settings_snapshot.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/browser/safe_browsing/settings_reset_prompt/settings_reset_prompt_config.h"
 #include "chrome/browser/search_engines/template_url_service_factory.h"
 #include "chrome/common/extensions/manifest_handlers/settings_overrides_handler.h"
@@ skipping 248 matching lines @@
 SettingsResetPromptModel::ResetState
 SettingsResetPromptModel::startup_urls_reset_state() const {
   return startup_urls_reset_state_;
 }
 
 const SettingsResetPromptModel::ExtensionMap&
 SettingsResetPromptModel::extensions_to_disable() const {
   return extensions_to_disable_;
 }
 
+void SettingsResetPromptModel::ReportUmaMetrics() const {
+  UMA_HISTOGRAM_BOOLEAN("SettingsResetPrompt.PromptWanted",
+                        ShouldPromptForReset());
+  UMA_HISTOGRAM_ENUMERATION("SettingsResetPrompt.DefaultSearchResetState",
+                            default_search_reset_state(), RESET_STATE_MAX);
+  UMA_HISTOGRAM_ENUMERATION("SettingsResetPrompt.StartupUrlsResetState",
+                            startup_urls_reset_state(), RESET_STATE_MAX);
+  UMA_HISTOGRAM_ENUMERATION("SettingsResetPrompt.HomepageResetState",
+                            homepage_reset_state(), RESET_STATE_MAX);
+  UMA_HISTOGRAM_SPARSE_SLOWLY("SettingsResetPrompt.NumberOfExtensionsToDisable",

[jwd, 2017/03/07 18:08:37]

I'm not super keen on this being sparse, since it can have arbitrary values
(determined by the client). Although in this case it's not a problem on the
client, and will be more memory efficient than a count histogram, when
aggregating during analysis, the histogram becomes arbitrarily large, causing
problems.

Do you need exact numbers for each emit? Using a count histogram will give you
an exact sum when aggregating, and the distribution.

[alito, 2017/03/07 20:42:05]

Changed this to a count histogram. I think that will work just as well for this
case. Thx.

+                              extensions_to_disable().size());
+  UMA_HISTOGRAM_SPARSE_SLOWLY(
+      "SettingsResetPrompt.DelayBeforePromptParam",
+      prompt_config_->delay_before_prompt().InSeconds());
+}
+
 // static
 void SettingsResetPromptModel::OnSettingsFetched(
     Profile* profile,
     std::unique_ptr<SettingsResetPromptConfig> prompt_config,
     SettingsResetPromptModel::CreateCallback callback,
     std::unique_ptr<BrandcodedDefaultSettings> default_settings) {
   DCHECK(profile);
   DCHECK(prompt_config);
   DCHECK(default_settings);
 
@@ skipping 225 matching lines @@
           GetExtension(profile_, extension_id);
       if (extension && management_policy->MustRemainEnabled(extension, nullptr))
         return true;
     }
   }
 
   return false;
 }
 
 }  // namespace safe_browsing.