Reland of Add EnabledStateObserver to BackgroundTracingManager

content/browser/tracing/background_tracing_manager_impl.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 CONTENT_BROWSER_TRACING_BACKGROUND_TRACING_MANAGER_IMPL_H_
 #define CONTENT_BROWSER_TRACING_BACKGROUND_TRACING_MANAGER_IMPL_H_
 
 #include <memory>
 
 #include "base/lazy_instance.h"
 #include "base/macros.h"
 #include "base/memory/ref_counted_memory.h"
 #include "base/memory/weak_ptr.h"
 #include "base/metrics/histogram.h"
 #include "content/browser/tracing/background_tracing_config_impl.h"
 #include "content/browser/tracing/tracing_controller_impl.h"
 #include "content/public/browser/background_tracing_manager.h"
 
 namespace content {
 
 class BackgroundTracingRule;
 class TracingDelegate;
 
 class BackgroundTracingManagerImpl : public BackgroundTracingManager {
  public:
-  static CONTENT_EXPORT BackgroundTracingManagerImpl* GetInstance();
+  // Enabled state observers get a callback when the state of background tracing
+  // changes.
+  class CONTENT_EXPORT EnabledStateObserver {
+   public:
+    // Called when the activation of a background tracing scenario is
+    // successful.
+    virtual void OnScenarioActivated(
+        const BackgroundTracingConfigImpl* config) = 0;
+
+    // Called after tracing is enabled on all processes because the rule was
+    // triggered.
+    virtual void OnTracingEnabled(
+        BackgroundTracingConfigImpl::CategoryPreset preset) = 0;
+
+    virtual ~EnabledStateObserver() = default;
+  };
+
+  CONTENT_EXPORT static BackgroundTracingManagerImpl* GetInstance();
 
   bool SetActiveScenario(std::unique_ptr<BackgroundTracingConfig>,
                          const ReceiveCallback&,
                          DataFiltering data_filtering) override;
   void WhenIdle(IdleCallback idle_callback) override;
 
   void TriggerNamedEvent(TriggerHandle, StartedFinalizingCallback) override;
   TriggerHandle RegisterTriggerType(const char* trigger_name) override;
 
   void OnHistogramTrigger(const std::string& histogram_name);
 
   void OnRuleTriggered(const BackgroundTracingRule* triggered_rule,
                        StartedFinalizingCallback callback);
   void AbortScenario();
   bool HasActiveScenario() override;
 
+  void OnStartTracingDone(BackgroundTracingConfigImpl::CategoryPreset preset);
+
+  // Add/remove EnabledStateObserver.
+  CONTENT_EXPORT void AddEnabledStateObserver(EnabledStateObserver* observer);
+  CONTENT_EXPORT void RemoveEnabledStateObserver(
+      EnabledStateObserver* observer);
+
   // For tests
   void InvalidateTriggerHandlesForTesting() override;
-  void SetTracingEnabledCallbackForTesting(
-      const base::Closure& callback) override;
   CONTENT_EXPORT void SetRuleTriggeredCallbackForTesting(
       const base::Closure& callback);
   void FireTimerForTesting() override;
   CONTENT_EXPORT bool IsTracingForTesting();
 
  private:
   BackgroundTracingManagerImpl();
   ~BackgroundTracingManagerImpl() override;
 
   void StartTracing(BackgroundTracingConfigImpl::CategoryPreset,
@@ skipping 39 matching lines @@
   std::unique_ptr<TracingTimer> tracing_timer_;
   ReceiveCallback receive_callback_;
   std::unique_ptr<base::DictionaryValue> last_triggered_rule_;
   bool is_gathering_;
   bool is_tracing_;
   bool requires_anonymized_data_;
   int trigger_handle_ids_;
 
   TriggerHandle triggered_named_event_handle_;
 
+  std::vector<EnabledStateObserver*> background_tracing_observer_list_;
+
   IdleCallback idle_callback_;
   base::Closure tracing_enabled_callback_for_testing_;
   base::Closure rule_triggered_callback_for_testing_;
 
   friend struct base::LazyInstanceTraitsBase<BackgroundTracingManagerImpl>;
 
   DISALLOW_COPY_AND_ASSIGN(BackgroundTracingManagerImpl);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_TRACING_BACKGROUND_TRACING_MANAGER_IMPL_H_