Fix mmap region iteration while no regions are recorded.

If no mmap regions are recorded, iteration failed since the
RegionSet (std::set) object is not initialized.

BUG=162208
R=willchan@chromium.org

Review URL: https://codereview.chromium.org/14769008

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@198878 0039d316-1c4b-4281-b951-d872f2087c98

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

@@ -646,8 +646,11 @@ void DeepHeapProfile::GlobalStats::SnapshotMaps(
 
   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)) {

third_party/tcmalloc/chromium/src/memory_region_map.cc

@@ -231,6 +231,8 @@ void MemoryRegionMap::Init(int max_stack_depth, bool use_buckets) {
     memset(bucket_table_, 0, table_bytes);
     num_buckets_ = 0;
   }
+  if (regions_ == NULL)  // init regions_
+    InitRegionSetLocked();
   Unlock();
   RAW_VLOG(10, "MemoryRegionMap Init done");
 }
@@ -533,6 +535,15 @@ void MemoryRegionMap::RestoreSavedBucketsLocked() {
   }
 }
 
+inline void MemoryRegionMap::InitRegionSetLocked() {
+  RAW_VLOG(12, "Initializing region set");
+  regions_ = regions_rep.region_set();
+  recursive_insert = true;
+  new(regions_) RegionSet();
+  HandleSavedRegionsLocked(&DoInsertRegionLocked);
+  recursive_insert = false;
+}
+
 inline void MemoryRegionMap::InsertRegionLocked(const Region& region) {
   RAW_CHECK(LockIsHeld(), "should be held (by this thread)");
   // We can be called recursively, because RegionSet constructor
@@ -552,14 +563,8 @@ inline void MemoryRegionMap::InsertRegionLocked(const Region& region) {
     // then increment saved_regions_count.
     saved_regions[saved_regions_count++] = region;
   } else {  // not a recusrive call
-    if (regions_ == NULL) {  // init regions_
-      RAW_VLOG(12, "Initializing region set");
-      regions_ = regions_rep.region_set();
-      recursive_insert = true;
-      new(regions_) RegionSet();
-      HandleSavedRegionsLocked(&DoInsertRegionLocked);
-      recursive_insert = false;
-    }
+    if (regions_ == NULL)  // init regions_
+      InitRegionSetLocked();
     recursive_insert = true;
     // Do the actual insertion work to put new regions into regions_:
     DoInsertRegionLocked(region);

third_party/tcmalloc/chromium/src/memory_region_map.h

@@ -361,6 +361,9 @@ class MemoryRegionMap {
   // table where all buckets eventually should be.
   static void RestoreSavedBucketsLocked();
 
+  // Initialize RegionSet regions_.
+  inline static void InitRegionSetLocked();
+
   // Wrapper around DoInsertRegionLocked
   // that handles the case of recursive allocator calls.
   inline static void InsertRegionLocked(const Region& region);