Make memory-infra tests register / unregister with thread safety

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 096eaf88487828c43ca9748182282eeed73df80a..092043deb61e4f24b98c74d25e8077965a91407d 100644
--- a/base/trace_event/memory_dump_manager.cc
+++ b/base/trace_event/memory_dump_manager.cc
@@ -277,6 +277,11 @@ void MemoryDumpManager::RegisterDumpProviderInternal(
       new MemoryDumpProviderInfo(mdp, name, std::move(task_runner), options,
                                  whitelisted_for_background_mode);
 
+  if (options.is_fast_polling_supported) {
+    DCHECK(!mdpinfo->task_runner) << "MemoryDumpProviders capable of fast "
+                                     "polling must NOT be thread bound.";
+  }
+
   {
     AutoLock lock(lock_);
     bool already_registered = !dump_providers_.insert(mdpinfo).second;
@@ -334,7 +339,7 @@ void MemoryDumpManager::UnregisterDumpProviderInternal(
     // - When the provider is removed from |dump_providers_for_polling_|.
     DCHECK(!(*mdp_iter)->owned_dump_provider);
     (*mdp_iter)->owned_dump_provider = std::move(owned_mdp);
-  } else if (subtle::NoBarrier_Load(&memory_tracing_enabled_)) {
+  } else {
     // If you hit this DCHECK, your dump provider has a bug.
     // Unregistration of a MemoryDumpProvider is safe only if:
     // - The MDP has specified a sequenced task runner affinity AND the
@@ -351,10 +356,6 @@ void MemoryDumpManager::UnregisterDumpProviderInternal(
   }
 
   if ((*mdp_iter)->options.is_fast_polling_supported && dump_thread_) {
-    DCHECK(take_mdp_ownership_and_delete_async)

[Primiano Tucci (use gerrit), 2016/12/21 11:44:25]

I'd still kjeep the DCHECK here, without the string, just for documentation and
code readability purposes.

[ssid, 2016/12/21 19:55:03]

Done.

-        << "MemoryDumpProviders capable of fast polling must NOT be thread "
-           "bound and hence must be destroyed using "
-           "UnregisterAndDeleteDumpProviderSoon()";
     dump_thread_->task_runner()->PostTask(
         FROM_HERE, Bind(&MemoryDumpManager::UnregisterPollingMDPOnDumpThread,
                         Unretained(this), *mdp_iter));
@@ -371,7 +372,6 @@ void MemoryDumpManager::UnregisterDumpProviderInternal(
 
 void MemoryDumpManager::RegisterPollingMDPOnDumpThread(
     scoped_refptr<MemoryDumpManager::MemoryDumpProviderInfo> mdpinfo) {
-  DCHECK(!mdpinfo->task_runner);
   AutoLock lock(lock_);
   dump_providers_for_polling_.insert(mdpinfo);
 }