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 cc8d0233d3d337456651fe9ae9cdadca82d22f0f..6411b959b5c29eee788ad77ae695bce01865e5ad 100644
--- a/base/metrics/persistent_histogram_allocator.h
+++ b/base/metrics/persistent_histogram_allocator.h
@@ -116,21 +116,39 @@ class BASE_EXPORT PersistentHistogramAllocator {
   static scoped_ptr<PersistentHistogramAllocator>
   ReleaseGlobalAllocatorForTesting();
 
-  // These helper methods perform SetGlobalAllocator() calls with allocators
-  // of the specified type and parameters.
+  // Create a global allocator using the passed-in memory |base|, |size|, and
+  // other parameters. Ownership of the memory segment remains with the caller.
   static void CreateGlobalAllocatorOnPersistentMemory(
       void* base,
       size_t size,
       size_t page_size,
       uint64_t id,
       StringPiece name);
+
+  // Create a global allocator using an internal block of memory of the
+  // specified |size| taken from the heap.
   static void CreateGlobalAllocatorOnLocalMemory(
       size_t size,
       uint64_t id,
       StringPiece name);
+
+  // Create a global allocator using a block of shared |memory| of the
+  // specified |size|. The allocator takes ownership of the shared memory
+  // and releases it upon destruction, though the memory will continue to
+  // live if other processes have access to it.
   static void CreateGlobalAllocatorOnSharedMemory(
+      scoped_ptr<SharedMemory> memory,
       size_t size,
-      const SharedMemoryHandle& handle);
+      uint64_t id,
+      StringPiece name);
+
+  // Create a global allocator using a block of shared memory accessed
+  // through the given |handle| and |size|. The allocator takes ownership
+  // of the handle and closes it upon destruction, though the memory will
+  // continue to live if other processes have access to it.
+  static void CreateGlobalAllocatorOnSharedMemoryHandle(
+      const SharedMemoryHandle& handle,
+      size_t size);
 
   // Import new histograms from the global PersistentHistogramAllocator. It's
   // possible for other processes to create histograms in the active memory