Call StatisticsRecorder::Initialize when a GlobalHistogramAllocator is created.

base/metrics/statistics_recorder.cc

Index: base/metrics/statistics_recorder.cc
diff --git a/base/metrics/statistics_recorder.cc b/base/metrics/statistics_recorder.cc
index a53f8f2a3c82f9a52f5e84a0930d158af0e189f8..6b1b0bfdea211e152e30929cac8216479a09786b 100644
--- a/base/metrics/statistics_recorder.cc
+++ b/base/metrics/statistics_recorder.cc
@@ -93,6 +93,17 @@ StatisticsRecorder::~StatisticsRecorder() {
 
 // static
 void StatisticsRecorder::Initialize() {
+  // Tests sometimes create local StatisticsRecorders in order to provide a
+  // contained environment of histograms that can be later discarded. If a
+  // true global instance gets created in this environment then it will
+  // eventually get disconnected when the local instance destructs and
+  // restores the previous state, resulting in no StatisticsRecorder at all.
+  // The global lazy instance, however, will remain valid thus ensuring that
+  // another never gets installed via this method. If a |histograms_| map
+  // exists then assume the StatisticsRecorder is already "initialized".
+  if (histograms_)
+    return;
+
   // Ensure that an instance of the StatisticsRecorder object is created.
   g_statistics_recorder_.Get();
 }