Fix crash in InvokeOnMemoryDump when tracing

base/trace_event/memory_dump_manager.h

Index: base/trace_event/memory_dump_manager.h
diff --git a/base/trace_event/memory_dump_manager.h b/base/trace_event/memory_dump_manager.h
index 92cc2f401b4d36f136199756d323df174adf38c2..a50c7ace70beb54e41599974f02b64608557b92d 100644
--- a/base/trace_event/memory_dump_manager.h
+++ b/base/trace_event/memory_dump_manager.h
@@ -123,6 +123,9 @@ class BASE_EXPORT MemoryDumpManager : public TraceLog::EnabledStateObserver {
   // Returns true if the dump mode is allowed for current tracing session.
   bool IsDumpModeAllowed(MemoryDumpLevelOfDetail dump_mode);
 
+  // Lets tests see if a dump provider is registered.
+  bool IsDumpProviderRegisteredForTesting(MemoryDumpProvider*);
+
   // Returns the MemoryDumpSessionState object, which is shared by all the
   // ProcessMemoryDump and MemoryAllocatorDump instances through all the tracing
   // session lifetime.