memory-infra: Start disentangling tracing from memory-infra

base/trace_event/trace_log.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_TRACE_LOG_H_
 #define BASE_TRACE_EVENT_TRACE_LOG_H_
 
 #include <stddef.h>
 #include <stdint.h>
 
@@ skipping 72 matching lines @@
   // TODO(ssid): Remove the default SetEnabled and IsEnabled. They should take
   // Mode as argument.
 
   // Disables tracing for all categories for the specified |modes_to_disable|
   // only. Only RECORDING_MODE is taken as default |modes_to_disable|.
   void SetDisabled();
   void SetDisabled(uint8_t modes_to_disable);
 
   // Returns true if TraceLog is enabled on recording mode.
   // Note: Returns false even if FILTERING_MODE is enabled.
-  bool IsEnabled() { return enabled_modes_ & RECORDING_MODE; }
+  virtual bool IsEnabled();

[hjd, 2017/04/13 14:16:59]

So I can mock.

 
   // Returns a bitmap of enabled modes from TraceLog::Mode.
   uint8_t enabled_modes() { return enabled_modes_; }
 
   // The number of times we have begun recording traces. If tracing is off,
   // returns -1. If tracing is on, then it returns the number of times we have
   // recorded a trace. By watching for this number to increment, you can
   // passively discover when a new trace has begun. This is then used to
   // implement the TRACE_EVENT_IS_NEW_TRACE() primitive.
   int GetNumTracesRecorded();
@@ skipping 12 matching lines @@
     virtual ~EnabledStateObserver() = default;
 
     // Called just after the tracing system becomes enabled, outside of the
     // |lock_|. TraceLog::IsEnabled() is true at this point.
     virtual void OnTraceLogEnabled() = 0;
 
     // Called just after the tracing system disables, outside of the |lock_|.
     // TraceLog::IsEnabled() is false at this point.
     virtual void OnTraceLogDisabled() = 0;
   };
-  void AddEnabledStateObserver(EnabledStateObserver* listener);
-  void RemoveEnabledStateObserver(EnabledStateObserver* listener);
+  virtual void AddEnabledStateObserver(EnabledStateObserver* listener);
+  virtual void RemoveEnabledStateObserver(EnabledStateObserver* listener);

[hjd, 2017/04/13 14:16:59]

So I can mock.

   bool HasEnabledStateObserver(EnabledStateObserver* listener) const;
 
   // Asynchronous enabled state listeners. When tracing is enabled or disabled,
   // for each observer, a task for invoking its appropriate callback is posted
   // to the thread from which AddAsyncEnabledStateObserver() was called. This
   // allows the observer to be safely destroyed, provided that it happens on the
   // same thread that invoked AddAsyncEnabledStateObserver().
   class BASE_EXPORT AsyncEnabledStateObserver {
    public:
     virtual ~AsyncEnabledStateObserver() = default;
@@ skipping 200 matching lines @@
                            TraceBufferRingBufferGetReturnChunk);
   FRIEND_TEST_ALL_PREFIXES(TraceEventTestFixture,
                            TraceBufferRingBufferHalfIteration);
   FRIEND_TEST_ALL_PREFIXES(TraceEventTestFixture,
                            TraceBufferRingBufferFullIteration);
   FRIEND_TEST_ALL_PREFIXES(TraceEventTestFixture, TraceBufferVectorReportFull);
   FRIEND_TEST_ALL_PREFIXES(TraceEventTestFixture,
                            ConvertTraceConfigToInternalOptions);
   FRIEND_TEST_ALL_PREFIXES(TraceEventTestFixture,
                            TraceRecordAsMuchAsPossibleMode);
+  friend class MockTraceLog;
 
   // This allows constructor and destructor to be private and usable only
   // by the Singleton class.
   friend struct DefaultSingletonTraits<TraceLog>;
 
   // MemoryDumpProvider implementation.
   bool OnMemoryDump(const MemoryDumpArgs& args,
                     ProcessMemoryDump* pmd) override;
 
   // Enable/disable each category group based on the current mode_,
@@ skipping 140 matching lines @@
 
   FilterFactoryForTesting filter_factory_for_testing_;
 
   DISALLOW_COPY_AND_ASSIGN(TraceLog);
 };
 
 }  // namespace trace_event
 }  // namespace base
 
 #endif  // BASE_TRACE_EVENT_TRACE_LOG_H_