memory-infra: Fix deadlock in MemoryDumpManager

base/trace_event/memory_dump_manager.cc

 // Copyright 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/trace_event/memory_dump_manager.h"
 
 #include <inttypes.h>
 #include <stdio.h>
 
 #include <algorithm>
@@ skipping 155 matching lines @@
       dumper_registrations_ignored_for_testing_(false),
       heap_profiling_enabled_(false) {
   g_next_guid.GetNext();  // Make sure that first guid is not zero.
 
   // At this point the command line may not be initialized but we try to
   // enable the heap profiler to capture allocations as soon as possible.
   EnableHeapProfilingIfNeeded();
 }
 
 MemoryDumpManager::~MemoryDumpManager() {
-  AutoLock lock(lock_);
-  if (dump_thread_) {
-    dump_thread_->Stop();
+  Thread* dump_thread = nullptr;
+  {
+    AutoLock lock(lock_);
+    if (dump_thread_) {
+      dump_thread = dump_thread_.get();
+    }
+  }
+  if (dump_thread) {
+    dump_thread->Stop();
+  }
+  {

[Primiano Tucci (use gerrit), 2017/05/11 13:53:27]

no need for these extra set of braces here

[hjd, 2017/05/11 14:18:41]

Done.

+    AutoLock lock(lock_);
     dump_thread_.reset();
   }
 }
 
 void MemoryDumpManager::EnableHeapProfilingIfNeeded() {
   if (heap_profiling_enabled_)
     return;
 
   if (!CommandLine::InitializedForCurrentProcess() ||
       !CommandLine::ForCurrentProcess()->HasSwitch(
@@ skipping 691 matching lines @@
   if (iter == process_dumps.end()) {
     std::unique_ptr<ProcessMemoryDump> new_pmd(
         new ProcessMemoryDump(heap_profiler_serialization_state, dump_args));
     iter = process_dumps.insert(std::make_pair(pid, std::move(new_pmd))).first;
   }
   return iter->second.get();
 }
 
 }  // namespace trace_event
 }  // namespace base