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

base/metrics/histogram_persistence.cc

 // Copyright (c) 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "base/metrics/histogram_persistence.h"
 
 #include "base/lazy_instance.h"
 #include "base/logging.h"
 #include "base/memory/scoped_ptr.h"
+#include "base/memory/shared_memory.h"
 #include "base/metrics/histogram.h"
 #include "base/metrics/histogram_base.h"
 #include "base/metrics/histogram_samples.h"
 #include "base/metrics/statistics_recorder.h"
 #include "base/synchronization/lock.h"
 
 namespace base {
 
 namespace {
 
@@ skipping 162 matching lines @@
 
 void SetPersistentHistogramMemoryAllocator(
     PersistentMemoryAllocator* allocator) {
   // Releasing or changing an allocator is extremely dangerous because it
   // likely has histograms stored within it. If the backing memory is also
   // also released, future accesses to those histograms will seg-fault.
   CHECK(!g_allocator);
   g_allocator = allocator;
 }
 
+SharedPersistentMemoryAllocator* CreateSharedPersistentHistogramMemoryAllocator(
+    size_t size,
+    StringPiece name,
+    uint64_t id) {
+  scoped_ptr<SharedMemory> shm(new SharedMemory());
+  shm->CreateAndMapAnonymous(size);
+  return new SharedPersistentMemoryAllocator(std::move(shm), id, name, false);
+}
+
+SharedPersistentMemoryAllocator* CreateSharedPersistentHistogramMemoryAllocator(
+    size_t size,
+    const SharedMemoryHandle& handle,
+    bool readonly) {
+  scoped_ptr<SharedMemory> shm(new SharedMemory(handle, readonly));
+  if (!shm->Map(size)) {
+    NOTREACHED();
+    return nullptr;
+  }
+  return new SharedPersistentMemoryAllocator(std::move(shm), 0, StringPiece(),
+                                             readonly);
+}
+
 PersistentMemoryAllocator* GetPersistentHistogramMemoryAllocator() {
   return g_allocator;
 }
 
 PersistentMemoryAllocator*
 ReleasePersistentHistogramMemoryAllocatorForTesting() {
   PersistentMemoryAllocator* allocator = g_allocator;
   if (!allocator)
     return nullptr;
 
@@ skipping 305 matching lines @@
     while (true) {
       HistogramBase* histogram = GetNextPersistentHistogram(g_allocator, &iter);
       if (!histogram)
         break;
       StatisticsRecorder::RegisterOrDeleteDuplicate(histogram);
     }
   }
 }
 
 }  // namespace base