Add UMA to report Preferences File Corruption

chrome/browser/prefs/pref_metrics_service.h

Index: chrome/browser/prefs/pref_metrics_service.h
diff --git a/chrome/browser/prefs/pref_metrics_service.h b/chrome/browser/prefs/pref_metrics_service.h
index fc48935c9f9f484917598ebee4b4ac1c33f691d6..a9da5bdd92da3449b5dc916b3a87302318a5fcef 100644
--- a/chrome/browser/prefs/pref_metrics_service.h
+++ b/chrome/browser/prefs/pref_metrics_service.h
@@ -10,11 +10,15 @@
 
 #include "base/memory/scoped_ptr.h"
 #include "base/memory/singleton.h"
+#include "base/memory/weak_ptr.h"
+#include "base/prefs/pref_change_registrar.h"
 #include "chrome/browser/prefs/synced_pref_change_registrar.h"
 #include "chrome/browser/profiles/profile.h"
 #include "components/browser_context_keyed_service/browser_context_keyed_service.h"
 #include "components/browser_context_keyed_service/browser_context_keyed_service_factory.h"
 
+class PrefRegistrySimple;
+
 // PrefMetricsService is responsible for recording prefs-related UMA stats.
 class PrefMetricsService : public BrowserContextKeyedService {
  public:
@@ -40,12 +44,10 @@ class PrefMetricsService : public BrowserContextKeyedService {
         content::BrowserContext* context) const OVERRIDE;
   };
 
- private:
-  // Use a map to convert domains to their histogram identifiers. Ids are
-  // defined in tools/metrics/histograms/histograms.xml and (usually) also in
-  // chrome/browser/search_engines/prepopulated_engines.json.
-  typedef std::map<std::string, int> DomainIdMap;
+  // Registers preferences in local settings.

[Mattias Nissler (ping if slow), 2013/08/15 10:14:51]

nit: s/local settings/local state/ for consistency with most of the rest of the
code.

[bbudge, 2013/08/15 17:33:49]

Done.

+  static void RegisterPrefs(PrefRegistrySimple* registry);
 
+ private:
   // Function to log a Value to a histogram
   typedef base::Callback<void(const std::string&, const Value*)>
       LogHistogramValueCallback;
@@ -82,7 +84,35 @@ class PrefMetricsService : public BrowserContextKeyedService {
                          const std::string& histogram_name,
                          const Value* value);
 
+  // Callback to receive a unique device_id. This is used to make it harder to
+  // spoof the preference value checks.
+  void GetDeviceIdCallback(const std::string& device_id);
+
+  // Checks the tracked preferences against their last known values and reports
+  // any discrepancies. This must be called after |device_id| has been set by
+  // GetDeviceIdCallback.
+  void CheckTrackedPreferences();
+
+  // Updates the hash of the tracked preference in local settings. This must be

[Mattias Nissler (ping if slow), 2013/08/15 10:14:51]

local state

[bbudge, 2013/08/15 17:33:49]

Done.

+  // called after |device_id| has been set by GetDeviceIdCallback.
+  void UpdateTrackedPreference(const char* path);
+
+  // Removes the tracked preference from local settings. Returns 'true' iff. the

[Mattias Nissler (ping if slow), 2013/08/15 10:14:51]

local state

[bbudge, 2013/08/15 17:33:49]

Done.

+  // value was present.
+  bool RemoveTrackedPreference(const char* path);
+
+  // Gets the path to the preference value hash in local settings.

[Mattias Nissler (ping if slow), 2013/08/15 10:14:51]

local state

[bbudge, 2013/08/15 17:33:49]

Done.

+  std::string GetHashedPrefPath(const char* path);
+
+  // Computes an MD5 hash for the given preference value. Salts the hash with
+  // the pref name and the device id to make it harder to spoof.
+  std::string GetHashedPrefValue(const char* path, const base::Value* value);
+
+  base::WeakPtrFactory<PrefMetricsService> weak_factory_;
+
   Profile* profile_;
+  std::string device_id_;
+  PrefChangeRegistrar pref_registrar_;
   scoped_ptr<SyncedPrefChangeRegistrar> synced_pref_change_registrar_;
 };