Fix crash in InvokeOnMemoryDump when tracing

base/trace_event/memory_dump_manager.h

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef BASE_TRACE_EVENT_MEMORY_DUMP_MANAGER_H_
 #define BASE_TRACE_EVENT_MEMORY_DUMP_MANAGER_H_
 
 #include <stdint.h>
 
 #include <map>
@@ skipping 105 matching lines @@
   // TraceLog::EnabledStateObserver implementation.
   void OnTraceLogEnabled() override;
   void OnTraceLogDisabled() override;
 
   // Enable heap profiling if kEnableHeapProfiling is specified.
   void EnableHeapProfilingIfNeeded();
 
   // 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.
   const scoped_refptr<MemoryDumpSessionState>& session_state_for_testing()
       const {
     return session_state_;
   }
 
   // Returns a unique id for identifying the processes. The id can be
   // retrieved by child processes only when tracing is enabled. This is
@@ skipping 266 matching lines @@
   }
 
  private:
   DISALLOW_COPY_AND_ASSIGN(MemoryDumpManagerDelegate);
 };
 
 }  // namespace trace_event
 }  // namespace base
 
 #endif  // BASE_TRACE_EVENT_MEMORY_DUMP_MANAGER_H_