Adds a method to the Performance Monitor Database to fetch the most recent metric.

chrome/browser/performance_monitor/database.cc

Index: chrome/browser/performance_monitor/database.cc
diff --git a/chrome/browser/performance_monitor/database.cc b/chrome/browser/performance_monitor/database.cc
index 8eb135080a00cedf9b51c82893712d7fc4520b0b..5844ff237728d931aae7bcf299349b2d8f152bed 100644
--- a/chrome/browser/performance_monitor/database.cc
+++ b/chrome/browser/performance_monitor/database.cc
@@ -379,6 +379,23 @@ std::vector<std::string> Database::GetActiveActivities(
   return results;
 }
 
+bool Database::GetRecentStatsForActivityAndMetric(
+    const std::string& activity,
+    MetricType metric,
+    MetricInfo* info) {
+  CHECK(!content::BrowserThread::CurrentlyOn(content::BrowserThread::UI));
+  std::string recent_map_key = CreateRecentMapKey(metric, activity);
+  if (!recent_map_.count(recent_map_key))

[Yoyo Zhou, 2012/08/02 11:54:57]

Use ContainsKey from stl_util.h.

+    return false;
+  std::string recent_key = recent_map_[recent_map_key];
+
+  std::string result;
+  leveldb::Status status = recent_db_->Get(read_options_, recent_key, &result);
+  if (status.ok())
+    *info = MetricInfo(SplitRecentKey(recent_key).time, result);
+  return status.ok();
+}
+
 Database::MetricInfoVector Database::GetStatsForActivityAndMetric(
     const std::string& activity, MetricType metric_type,
     const base::Time& start, const base::Time& end) {