Add log date to the metrics log

components/metrics/persisted_logs.h

Index: components/metrics/persisted_logs.h
diff --git a/components/metrics/persisted_logs.h b/components/metrics/persisted_logs.h
index 73ad79a5b06e36a0e43aeebe06a44e5b615308a3..ff5de71ecc2039b7c02ba841e0993c4f83355f2e 100644
--- a/components/metrics/persisted_logs.h
+++ b/components/metrics/persisted_logs.h
@@ -72,6 +72,8 @@ class PersistedLogs {
   // Remove the staged log.
   void DiscardStagedLog();
 
+  void MigrateFromOldFormat(const char* old_pref_name);
+
   // True if a log has been staged.
   bool has_staged_log() const { return staged_log_index_ != -1; }
 
@@ -87,6 +89,12 @@ class PersistedLogs {
     return list_[staged_log_index_].hash;
   }
 
+  // Returns the timestamp of the element in the front of the list.
+  int staged_log_timestamp() const {
+    DCHECK(has_staged_log());
+    return list_[staged_log_index_].timestamp;
+  }
+
   // The number of elements currently stored.
   size_t size() const { return list_.size(); }
 
@@ -100,6 +108,9 @@ class PersistedLogs {
   // Reads the list from the ListValue.
   LogReadStatus ReadLogsFromPrefList(const base::ListValue& list);
 
+  // Reads the list from the ListValue in the old Log-hash pair format.
+  LogReadStatus ReadLogsFromPrefList_OldFormat(const base::ListValue& list);
+
   // A weak pointer to the PrefService object to read and write the preference
   // from.  Calling code should ensure this object continues to exist for the
   // lifetime of the PersistedLogs object.
@@ -117,7 +128,7 @@ class PersistedLogs {
   // Logs greater than this size will not be written to disk.
   const size_t max_log_size_;
 
-  struct LogHashPair {
+  struct LogInfo {
     // Initializes the members based on uncompressed |log_data|.
     void Init(const std::string& log_data);
 
@@ -126,10 +137,14 @@ class PersistedLogs {
 
     // The SHA1 hash of log, stored to catch errors from memory corruption.
     std::string hash;
+
+    // The timestamp of when the log was created in seconds. Seconds is enough
+    // as decision for removing old logs wouldn't need more granularity.
+    int timestamp;

[Alexei Svitkine (slow), 2016/09/28 18:50:30]

Add a ctor so that this value is initialized.

[gayane -on leave until 09-2017, 2016/09/28 20:50:50]

Done.

   };
   // A list of all of the stored logs, stored with SHA1 hashes to check for
   // corruption while they are stored in memory.
-  std::vector<LogHashPair> list_;
+  std::vector<LogInfo> list_;
 
   // The index and type of the log staged for upload. If nothing has been
   // staged, the index will be -1.