[Tracing] Disable registration of regular dump providers during tests

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 1c3c581d8ebece634081ce613e1057a0d0d70111..184546cfc951d0bb746f2ff9d32c08ad6399aa02 100644
--- a/base/trace_event/memory_dump_manager.cc
+++ b/base/trace_event/memory_dump_manager.cc
@@ -87,8 +87,6 @@ MemoryDumpManager* MemoryDumpManager::GetInstance() {
 
 // static
 void MemoryDumpManager::SetInstanceForTesting(MemoryDumpManager* instance) {
-  if (instance)
-    instance->skip_core_dumpers_auto_registration_for_testing_ = true;
   g_instance_for_testing = instance;
 }
 
@@ -97,7 +95,7 @@ MemoryDumpManager::MemoryDumpManager()
       memory_tracing_enabled_(0),
       tracing_process_id_(kInvalidTracingProcessId),
       system_allocator_pool_name_(nullptr),
-      skip_core_dumpers_auto_registration_for_testing_(false),
+      ignore_registrations_for_testing_(false),
       disable_periodic_dumps_for_testing_(false) {
   g_next_guid.GetNext();  // Make sure that first guid is not zero.
 }
@@ -110,9 +108,6 @@ void MemoryDumpManager::Initialize() {
   TRACE_EVENT0(kTraceCategory, "init");  // Add to trace-viewer category list.
   trace_event::TraceLog::GetInstance()->AddEnabledStateObserver(this);
 
-  if (skip_core_dumpers_auto_registration_for_testing_)
-    return;
-
   // Enable the core dump providers.
 #if !defined(OS_NACL)
   RegisterDumpProvider(ProcessMemoryTotalsDumpProvider::GetInstance());
@@ -150,8 +145,12 @@ void MemoryDumpManager::SetDelegate(MemoryDumpManagerDelegate* delegate) {
 void MemoryDumpManager::RegisterDumpProvider(
     MemoryDumpProvider* mdp,
     const scoped_refptr<SingleThreadTaskRunner>& task_runner) {
+  AutoLock lock(lock_);
+
+  if (ignore_registrations_for_testing_)
+    return;
+
   MemoryDumpProviderInfo mdp_info(mdp, task_runner);
-  AutoLock lock(lock_);
   auto iter_new = dump_providers_.insert(mdp_info);
 
   // If there was a previous entry, replace it with the new one. This is to deal