[tracing] Fix MemoryDumpManager to support startup tracing

content/child/child_thread_impl.cc

Index: content/child/child_thread_impl.cc
diff --git a/content/child/child_thread_impl.cc b/content/child/child_thread_impl.cc
index 8f0d93c67c36a9dbc2261ee635b734c0143e15ea..08c2075f7faef7542f94dc26911e6a202ab93eda 100644
--- a/content/child/child_thread_impl.cc
+++ b/content/child/child_thread_impl.cc
@@ -28,7 +28,6 @@
 #include "base/synchronization/lock.h"
 #include "base/thread_task_runner_handle.h"
 #include "base/threading/thread_local.h"
-#include "base/trace_event/memory_dump_manager.h"
 #include "base/tracked_objects.h"
 #include "components/tracing/child_trace_message_filter.h"
 #include "content/child/child_discardable_shared_memory_manager.h"
@@ -495,8 +494,6 @@ void ChildThreadImpl::Init(const Options& options) {
       ::HeapProfilerStop, ::GetHeapProfile));
 #endif
 
-  base::trace_event::MemoryDumpManager::GetInstance()->Initialize();
-
   shared_bitmap_manager_.reset(
       new ChildSharedBitmapManager(thread_safe_sender()));