leveldb: Add DBTracker for exposing databases to Chrome's memory-infra.

chrome/browser/android/history_report/usage_reports_buffer_backend.cc

Index: chrome/browser/android/history_report/usage_reports_buffer_backend.cc
diff --git a/chrome/browser/android/history_report/usage_reports_buffer_backend.cc b/chrome/browser/android/history_report/usage_reports_buffer_backend.cc
index c8214a0567f9aa9e067dc01f79eb02fc7763f204..cac8e1898d589d03f2d326fb6dc963e0d9afbafc 100644
--- a/chrome/browser/android/history_report/usage_reports_buffer_backend.cc
+++ b/chrome/browser/android/history_report/usage_reports_buffer_backend.cc
@@ -38,14 +38,14 @@ bool UsageReportsBufferBackend::Init() {
   options.max_open_files = 0;  // Use minimum number of files.
   std::string path = db_file_name_.value();
   leveldb::DB* db = NULL;
-  leveldb::Status status = leveldb::DB::Open(options, path, &db);
+  leveldb::Status status = leveldb_env::DBRegistry::Open(options, path, &db);
   UMA_HISTOGRAM_ENUMERATION("LevelDB.Open.UsageReportsBufferBackend",
                             leveldb_env::GetLevelDBStatusUMAValue(status),
                             leveldb_env::LEVELDB_STATUS_MAX);
   if (status.IsCorruption()) {
     LOG(ERROR) << "Deleting corrupt database";
     base::DeleteFile(db_file_name_, true);
-    status = leveldb::DB::Open(options, path, &db);
+    status = leveldb_env::DBRegistry::Open(options, path, &db);
   }
   if (status.ok()) {
     CHECK(db);