Multi-strategy based tracking.

chrome/browser/prefs/tracked_split_preference.cc

+// Copyright 2013 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/prefs/tracked_split_preference.h"
+
+#include <vector>
+
+#include "base/logging.h"
+#include "base/metrics/histogram.h"
+#include "base/values.h"
+
+TrackedSplitPreference::TrackedSplitPreference(
+    const std::string& pref_path,
+    size_t reporting_id,
+    size_t reporting_ids_count,
+    EnforcementLevel enforcement_level)
+    : TrackedPreference(reporting_id, reporting_ids_count, enforcement_level),
+      pref_path_(pref_path) {
+}
+
+void TrackedSplitPreference::StoreHash(const base::Value* value,
+                                       PrefHashStore* pref_hash_store) const {
+  const base::DictionaryValue* dict_value = NULL;
+  if (value && !value->GetAsDictionary(&dict_value)) {
+    NOTREACHED();
+    return;
+  }
+  pref_hash_store->StoreSplitHash(pref_path_, dict_value);
+}
+
+void TrackedSplitPreference::EnforceAndReport(
+    PrefHashStore* pref_hash_store,
+    base::DictionaryValue* pref_store_contents) const {
+  base::DictionaryValue* dict_value = NULL;
+  if (!pref_store_contents->GetDictionary(pref_path_, &dict_value) &&
+      pref_store_contents->Get(pref_path_, NULL)) {
+    // There should be a dictionary or nothing at |pref_path_|.
+    NOTREACHED();
+    return;
+  }
+
+  std::vector<std::string> invalid_keys;
+  PrefHashStore::ValueState value_state =
+      pref_hash_store->CheckSplitValue(pref_path_, dict_value, &invalid_keys);
+
+  if (value_state == PrefHashStore::CHANGED)
+    ReportSplitPreferenceChangedCount(invalid_keys.size());
+
+  ReportValidationResult(value_state);
+
+  ResetAction reset_action = GetAction(value_state);
+  ReportAction(reset_action);
+
+  if (reset_action == DO_RESET) {
+    if (value_state == PrefHashStore::CHANGED) {
+      DCHECK(!invalid_keys.empty());
+
+      for (std::vector<std::string>::const_iterator it =
+               invalid_keys.begin(); it != invalid_keys.end(); ++it) {
+        dict_value->Remove(*it, NULL);
+      }
+    } else {
+      pref_store_contents->RemovePath(pref_path_, NULL);
+    }
+  }
+
+  if (value_state != PrefHashStore::UNCHANGED) {
+    // Store the hash for the new value (whether it was reset or not).
+    const base::DictionaryValue* new_dict_value = NULL;
+    pref_store_contents->GetDictionary(pref_path_, &new_dict_value);
+    pref_hash_store->StoreSplitHash(pref_path_, new_dict_value);
+  }
+}
+
+void TrackedSplitPreference::ReportSplitPreferenceChangedCount(
+    size_t count) const {
+  // The histogram below is an expansion of the UMA_HISTOGRAM_COUNTS_100 macro
+  // adapted to allow for a dynamically suffixed histogram name.
+  // Note: The factory creates and owns the histogram.
+  base::HistogramBase* histogram =
+      base::LinearHistogram::FactoryGet(
+          "Settings.TrackedSplitPreferenceChanged." + pref_path_,
+          1,
+          100,  // Allow counts up to 100.
+          101,
+          base::HistogramBase::kUmaTargetedHistogramFlag);
+  histogram->Add(count);
+}