Fix crash in InvokeOnMemoryDump when tracing

base/trace_event/memory_dump_manager.cc

Index: base/trace_event/memory_dump_manager.cc
diff --git a/base/trace_event/memory_dump_manager.cc b/base/trace_event/memory_dump_manager.cc
index 5a54a773c5e4eb8b7eb816000855e23dc0374780..678c1c2397266e983ce96d7b3ebd99cab6a2e7a5 100644
--- a/base/trace_event/memory_dump_manager.cc
+++ b/base/trace_event/memory_dump_manager.cc
@@ -483,6 +483,18 @@ void MemoryDumpManager::RequestGlobalDump(
   RequestGlobalDump(dump_type, level_of_detail, MemoryDumpCallback());
 }
 
+bool MemoryDumpManager::IsDumpProviderRegisteredForTesting(
+    MemoryDumpProvider* provider) {
+  AutoLock lock(lock_);
+
+  auto mdp_iter = dump_providers_.begin();

[Primiano Tucci (use gerrit), 2017/03/15 12:44:40]

you can use C++11 foreach these days, which is quite neat. Makes it look like a
20th century language. 
It should be something like:

for (const auto& mdp : dump_providers) ...

[hjd, 2017/03/15 14:23:12]

Done, thanks!

+  for (; mdp_iter != dump_providers_.end(); ++mdp_iter) {
+    if ((*mdp_iter)->dump_provider == provider)
+      return true;
+  }
+  return false;
+}
+
 void MemoryDumpManager::CreateProcessDump(const MemoryDumpRequestArgs& args,
                                           const MemoryDumpCallback& callback) {
   TRACE_EVENT_NESTABLE_ASYNC_BEGIN0(kTraceCategory, "ProcessMemoryDump",