Simplify webrtc::voe::MonitorModule and remove the .cc file.

webrtc/voice_engine/monitor_module.h

 /*
  *  Copyright (c) 2012 The WebRTC project authors. All Rights Reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
 #ifndef WEBRTC_VOICE_ENGINE_MONITOR_MODULE_H
 #define WEBRTC_VOICE_ENGINE_MONITOR_MODULE_H
 
-#include "webrtc/base/criticalsection.h"
-#include "webrtc/base/thread_annotations.h"
 #include "webrtc/modules/include/module.h"
-#include "webrtc/typedefs.h"
-#include "webrtc/voice_engine/voice_engine_defines.h"
-
-class MonitorObserver
-{
-public:
-    virtual void OnPeriodicProcess() = 0;
-protected:
-    virtual ~MonitorObserver() {}
-};
-
 
 namespace webrtc {
 namespace voe {
 
-class MonitorModule : public Module
-{
-public:
-    int32_t RegisterObserver(MonitorObserver& observer);
+// When associated with a ProcessThread, calls a callback method
+// |OnPeriodicProcess()| implemented by the |Observer|.
+// TODO(tommi): This could be replaced with PostDelayedTask().
+template <typename Observer>
+class MonitorModule : public Module {
+ public:
+  explicit MonitorModule(Observer* observer) : observer_(observer) {}
+  ~MonitorModule() override {}
 
-    int32_t DeRegisterObserver();
+ private:
+  int64_t TimeUntilNextProcess() override { return 1000; }
+  void Process() override { observer_->OnPeriodicProcess(); }

[henrika_webrtc, 2017/02/28 08:24:21]

To me it looks like TransmitMixer::OnPeridodicProcess contains e.g
VE_TYPING_NOISE_OFF_WARNING and VE_SATURATION_WARNING. Instead of improving this
class even more (by using delayed PostTask), it might be worth considering if it
can be removed completely. Henrik L should know if any of the callbacks are used
today.

[tommi, 2017/02/28 08:38:41]

Good point... I looked around for VE_SATURATION_WARNING and all I can find is
this:

    printf("  SATURATION WARNING \n");

in voe_cmd_test.cc

It would be good to delete this if it's not being used.  We'd get rid of one
lock inside of TransmitMixer::ProcessAudio.  Added a TODO for now in this file,
with details.

 
-    MonitorModule();
-
-    virtual ~MonitorModule();
-public: // module
- int64_t TimeUntilNextProcess() override;
-
- void Process() override;
-
-private:
-    rtc::CriticalSection _callbackCritSect;
-    MonitorObserver* _observerPtr GUARDED_BY(_callbackCritSect);
-    int64_t _lastProcessTime;
+  Observer* const observer_;
 };
 
 }  // namespace voe
-
 }  // namespace webrtc
 
-#endif // VOICE_ENGINE_MONITOR_MODULE
+#endif  // VOICE_ENGINE_MONITOR_MODULE