Revert "Create and pass shared-histogram-allocator from browser to renderer."

base/metrics/persistent_histogram_allocator.h

Index: base/metrics/persistent_histogram_allocator.h
diff --git a/base/metrics/persistent_histogram_allocator.h b/base/metrics/persistent_histogram_allocator.h
index b2038c4314c704f572771648b76410fdcffd03b0..12ac68500cb202c63ff8e813d6b16762022f6e85 100644
--- a/base/metrics/persistent_histogram_allocator.h
+++ b/base/metrics/persistent_histogram_allocator.h
@@ -116,6 +116,13 @@ class BASE_EXPORT PersistentHistogramAllocator {
   // Histogram containing creation results. Visible for testing.
   static HistogramBase* GetCreateHistogramResultHistogram();
 
+  // This access to the persistent allocator is only for testing; it extracts
+  // the current allocator completely. This allows easy creation of histograms
+  // within persistent memory segments which can then be extracted and used
+  // in other ways.
+  static std::unique_ptr<PersistentHistogramAllocator>
+  ReleaseGlobalAllocatorForTesting();
+
  protected:
   // The structure used to hold histogram data in persistent memory. It is
   // defined and used entirely within the .cc file.