New Task Manager - Phase 1.1: Implement Browser Process Task Providing

chrome/browser/task_management/providers/task_provider.h

Index: chrome/browser/task_management/providers/task_provider.h
diff --git a/chrome/browser/task_management/providers/task_provider.h b/chrome/browser/task_management/providers/task_provider.h
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+// 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 CHROME_BROWSER_TASK_MANAGEMENT_PROVIDERS_TASK_PROVIDER_H_
+#define CHROME_BROWSER_TASK_MANAGEMENT_PROVIDERS_TASK_PROVIDER_H_
+
+#include "chrome/browser/task_management/providers/task_provider_observer.h"
+
+namespace task_management {
+
+// Defines the interface for task providers. A concrete task provider must be
+// able to collect all the tasks of a particular type which this provider
+// supports as well as track any tasks addition / removal. Once StartUpdating()
+// is called, the provider is responsible for notifying the observer about the
+// tasks it's tracking. The TaskProviders own the tasks they provide.
+class TaskProvider {
+ public:
+  TaskProvider();
+  virtual ~TaskProvider();
+
+  // Should return the task associated to the specified IDs from a
+  // |content::ResourceRequestInfo| that represents a |URLRequest|. A value of
+  // nullptr will be returned if the desired task does not belong to this
+  // provider.
+  //
+  // |origin_pid| is the PID of the originating process of the URLRequest, if
+  // the request is sent on behalf of another process. Otherwise it's 0.
+  // |child_id| is the unique ID of the host of the child process requestor.
+  // |route_id| is the ID of the IPC route for the URLRequest (this identifies
+  // the RenderView or like-thing in the renderer that the request gets routed
+  // to).
+  virtual Task* GetTaskOfUrlRequest(int origin_pid,
+                                    int child_id,
+                                    int route_id) = 0;
+
+  // Set the sole observer of this provider. It's an error to set an observer
+  // if there's already one there.
+  void SetObserver(TaskProviderObserver* observer);
+
+  // Clears the currently set observer for this provider. It's an error to clear
+  // the observer if there's no one set.
+  void ClearObserver();
+
+ protected:
+  // Used by concrete task providers to notify the observer of tasks addition/
+  // removal. These methods should only be called after StartUpdating() has been
+  // called and before StopUpdating() is called.
+  void NotifyObserverTaskAdded(Task* task) const;
+  void NotifyObserverTaskRemoved(Task* task) const;
+
+ private:
+  // This will be called once an observer is set for this provider. When it is
+  // called, the concrete provider must notify the observer of all pre-existing
+  // tasks as well as track new addition and terminations and notify the
+  // observer of these changes.
+  virtual void StartUpdating() = 0;
+
+  // This will be called once the observer is cleared, at which point the
+  // provider can stop tracking tasks addition / removal and can clear its own
+  // resources.
+  virtual void StopUpdating() = 0;
+
+  // We support only one single obsever which will be the sampler in this case.
+  TaskProviderObserver* observer_;
+
+  DISALLOW_COPY_AND_ASSIGN(TaskProvider);
+};
+
+}  // namespace task_management
+
+#endif  // CHROME_BROWSER_TASK_MANAGEMENT_PROVIDERS_TASK_PROVIDER_H_