Fix mmap region iteration while no regions are recorded.

third_party/tcmalloc/chromium/src/deep-heap-profile.cc

 // Copyright (c) 2012 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.
 
 // ---
 // Author: Sainbayar Sukhbaatar
 //         Dai Mikurube
 //
 
 #include "deep-heap-profile.h"
@@ skipping 628 matching lines @@
   char* filename;
   enum MapsRegionType type;
   for (int i = 0; i < NUMBER_OF_MAPS_REGION_TYPES; ++i) {
     all_[i].Initialize();
     unhooked_[i].Initialize();
   }
   profiled_mmap_.Initialize();
 
   MemoryRegionMap::RegionIterator mmap_iter =
       MemoryRegionMap::BeginRegionLocked();
-  DeepBucket* deep_bucket = GetInformationOfMemoryRegion(
-      mmap_iter, memory_residence_info_getter, deep_profile);
+  DeepBucket* deep_bucket = NULL;
+  if (mmap_iter != MemoryRegionMap::EndRegionLocked()) {
+    deep_bucket = GetInformationOfMemoryRegion(
+        mmap_iter, memory_residence_info_getter, deep_profile);
+  }
 
   while (procmaps_iter.Next(&vma_start_addr, &vma_last_addr,
                             &flags, &offset, &inode, &filename)) {
     if (mmap_dump_buffer) {
       char buffer[1024];
       int written = procmaps_iter.FormatLine(buffer, sizeof(buffer),
                                              vma_start_addr, vma_last_addr,
                                              flags, offset, inode, filename, 0);
       mmap_dump_buffer->AppendString(buffer, 0);
     }
@@ skipping 259 matching lines @@
 }
 
 DeepHeapProfile::~DeepHeapProfile() {
 }
 
 int DeepHeapProfile::FillOrderedProfile(char raw_buffer[], int buffer_size) {
   return heap_profile_->FillOrderedProfile(raw_buffer, buffer_size);
 }
 
 #endif  // USE_DEEP_HEAP_PROFILE