memory-infra: Remove is_enabled_ from MDM

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 294 matching lines @@
   // Function provided by the embedder to handle global dump requests.
   RequestGlobalDumpFunction request_dump_function_;
 
   // True when current process coordinates the periodic dump triggering.
   bool is_coordinator_;
 
   // Protects from concurrent accesses to the local state, eg: to guard against
   // disabling logging while dumping on another thread.
   Lock lock_;
 
-  // Optimization to avoid attempting any memory dump (i.e. to not walk an empty
-  // dump_providers_enabled_ list) when tracing is not enabled.
-  subtle::AtomicWord is_enabled_;
-
   // Thread used for MemoryDumpProviders which don't specify a task runner
   // affinity.
   std::unique_ptr<Thread> dump_thread_;
 
   // The unique id of the child process. This is created only for tracing and is
   // expected to be valid only when tracing is enabled.
   uint64_t tracing_process_id_;
 
   // When true, calling |RegisterMemoryDumpProvider| is a no-op.
   bool dumper_registrations_ignored_for_testing_;
 
   // Whether new memory dump providers should be told to enable heap profiling.
   bool heap_profiling_enabled_;
 
   DISALLOW_COPY_AND_ASSIGN(MemoryDumpManager);
 };
 
 }  // namespace trace_event
 }  // namespace base
 
 #endif  // BASE_TRACE_EVENT_MEMORY_DUMP_MANAGER_H_