Don't crash in StatisticsRecorder if VLOG level changes.

This happens, for instance, when specifying "--v" command-line argument
to browser_tests (which is suspicious itself, but nevertheless
DCHECK'ing here is not the best behavior).

BUG=487283

Review URL: https://codereview.chromium.org/1132203004

Cr-Commit-Position: refs/heads/master@{#329670}

base/metrics/statistics_recorder.cc

@@ -286,8 +286,6 @@ StatisticsRecorder::StatisticsRecorder() {
 
 // static
 void StatisticsRecorder::DumpHistogramsToVlog(void* instance) {
-  DCHECK(VLOG_IS_ON(1));
-
   string output;
   StatisticsRecorder::WriteGraph(std::string(), &output);
   VLOG(1) << output;