Delay PersistentHistogramAllocator creation until it's known to be used.

content/browser/browser_main_runner.cc

Index: content/browser/browser_main_runner.cc
diff --git a/content/browser/browser_main_runner.cc b/content/browser/browser_main_runner.cc
index 44431a05e362386f85d2ac6776741b8060638129..96a3454f1499edbb0211afbcdb1ba8024cb6e2bc 100644
--- a/content/browser/browser_main_runner.cc
+++ b/content/browser/browser_main_runner.cc
@@ -11,7 +11,6 @@
 #include "base/macros.h"
 #include "base/metrics/histogram.h"
 #include "base/metrics/histogram_macros.h"
-#include "base/metrics/persistent_histogram_allocator.h"
 #include "base/metrics/statistics_recorder.h"
 #include "base/profiler/scoped_profile.h"
 #include "base/profiler/scoped_tracker.h"
@@ -82,16 +81,6 @@ class BrowserMainRunnerImpl : public BrowserMainRunner {
 
       const base::TimeTicks start_time_step1 = base::TimeTicks::Now();
 
-      // Create persistent/shared memory and allow histograms to be stored in
-      // it. Memory that is not actualy used won't be physically mapped by the
-      // system. BrowserMetrics usage, as reported in UMA, peaked around 1.9MiB
-      // as of 2016-02-20.
-      base::GlobalHistogramAllocator::CreateWithLocalMemory(
-          3 << 20,     // 3 MiB
-          0x935DDD43,  // SHA1(BrowserMetrics)
-          "BrowserMetrics");
-      base::GlobalHistogramAllocator::Disable();  // Enabled by experiment only.
-
       SkGraphics::Init();
 
       if (parameters.command_line.HasSwitch(switches::kWaitForDebugger))