tracing: fix edge case when dumping while trace being disabled

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 220 matching lines @@
     // the dump. This is a copy of |dump_providers_| at the beginning of a dump
     // and becomes empty at the end, when all dump providers have been invoked.
     std::vector<scoped_refptr<MemoryDumpProviderInfo>> pending_dump_providers;
 
     // The trace-global session state.
     scoped_refptr<MemoryDumpSessionState> session_state;
 
     // Callback passed to the initial call to CreateProcessDump().
     MemoryDumpCallback callback;
 
+    // The |success| field that will be passed as argument to the |callback|.
+    bool dump_successful;
+
     // The thread on which FinalizeDumpAndAddToTrace() (and hence |callback|)
     // should be invoked. This is the thread on which the initial
     // CreateProcessDump() request was called.
     const scoped_refptr<SingleThreadTaskRunner> callback_task_runner;
 
     // The thread on which unbound dump providers should be invoked.
     // This is essentially |dump_thread_|.task_runner() but needs to be kept
     // as a separate variable as it needs to be accessed by arbitrary dumpers'
     // threads outside of the lock_ to avoid races when disabling tracing.
     // It is immutable for all the duration of a tracing session.
@@ skipping 92 matching lines @@
   }
 
  private:
   DISALLOW_COPY_AND_ASSIGN(MemoryDumpManagerDelegate);
 };
 
 }  // namespace trace_event
 }  // namespace base
 
 #endif  // BASE_TRACE_EVENT_MEMORY_DUMP_MANAGER_H_