Refactor Timer classes in preparation for landing FrameTimers.

third_party/WebKit/Source/platform/Timer.h

Index: third_party/WebKit/Source/platform/Timer.h
diff --git a/third_party/WebKit/Source/platform/Timer.h b/third_party/WebKit/Source/platform/Timer.h
index 8245b3adbf1a499f5fbfa49ee5816444badc9fcf..048ac02f7d17fb541d7499f927f086e64e0692d9 100644
--- a/third_party/WebKit/Source/platform/Timer.h
+++ b/third_party/WebKit/Source/platform/Timer.h
@@ -44,7 +44,6 @@ namespace blink {
 class PLATFORM_EXPORT TimerBase {
     WTF_MAKE_NONCOPYABLE(TimerBase);
 public:
-    TimerBase();

[dcheng, 2016/07/28 13:09:51]

This was only used by three subclasses: SuspendableTImer, SecureTextTimer and
XMLHttpRequestProgessEventThrottle. For now, they just keep the current
behavior, but we'll likely want to revisit.

[haraken, 2016/07/28 14:44:46]

I believe that SuspendableTImer was intentionally using TimerBase() because
SuspendableTImer wants to use the timer task runner. But I'm not sure if
SecureTextTimer and XMLHttpRequestProgessEventThrottle had that intention :)

[haraken, 2016/07/28 17:38:15]

So, ignore this comment.

[dcheng, 2016/07/29 02:23:18]

!!! I made a mistake. I changed SuspendableTimer to use the timer task runner
now instead of the unthrottled task runner (I accidentally confused myself with
the naming yesterday)

     explicit TimerBase(WebTaskRunner*);
     virtual ~TimerBase();
 
@@ -77,7 +76,8 @@ public:
     };
 
 protected:
-    static WebTaskRunner* UnthrottledWebTaskRunner();
+    static WebTaskRunner* getTimerTaskRunner();
+    static WebTaskRunner* getDefaultTaskRunner();
 
 private:
     virtual void fired() = 0;
@@ -155,23 +155,16 @@ public:
 };
 
 template <typename TimerFiredClass>
-class Timer : public TimerBase {
+class TaskRunnerTimer : public TimerBase {
 public:
-    using TimerFiredFunction = void (TimerFiredClass::*)(Timer<TimerFiredClass>*);
+    using TimerFiredFunction = void (TimerFiredClass::*)(TimerBase*);
 
-    // TODO(dcheng): Consider removing this overload once all timers are using the
-    // appropriate task runner. https://crbug.com/624694
-    Timer(TimerFiredClass* o, TimerFiredFunction f)
-        : m_object(o), m_function(f)
-    {
-    }
-
-    Timer(TimerFiredClass* o, TimerFiredFunction f, WebTaskRunner* webTaskRunner)
+    TaskRunnerTimer(WebTaskRunner* webTaskRunner, TimerFiredClass* o, TimerFiredFunction f)
         : TimerBase(webTaskRunner), m_object(o), m_function(f)
     {
     }
 
-    ~Timer() override { }
+    ~TaskRunnerTimer() override { }
 
 protected:
     void fired() override
@@ -197,17 +190,33 @@ private:
     TimerFiredFunction m_function;
 };
 
+// TODO(dcheng): Consider removing this overload once all timers are using the
+// appropriate task runner. https://crbug.com/624694
+template <typename TimerFiredClass>
+class Timer : public TaskRunnerTimer<TimerFiredClass> {
+public:
+    using TimerFiredFunction = typename TaskRunnerTimer<TimerFiredClass>::TimerFiredFunction;

[dcheng, 2016/07/28 13:09:51]

I switched these to using type aliases, because it's more robust to any changes
in the signature in the base template.

To avoid having to define a slightly different typedef for each one, I just use
TimerBase* as the parameter: it's good enough for all the uses we care about
(most callbacks don't even care), and it's less typing.

+
+    ~Timer() override { }
+
+    Timer(TimerFiredClass* timerFiredClass, TimerFiredFunction timerFiredFunction)
+        : TaskRunnerTimer<TimerFiredClass>(TimerBase::getTimerTaskRunner(), timerFiredClass, timerFiredFunction)
+    {
+    }
+};
+
+
 // This subclass of Timer posts its tasks on the current thread's default task runner.
 // Tasks posted on there are not throttled when the tab is in the background.
 template <typename TimerFiredClass>
-class UnthrottledTimer : public Timer<TimerFiredClass> {
+class UnthrottledThreadTimer : public TaskRunnerTimer<TimerFiredClass> {
 public:
-    using TimerFiredFunction = void (TimerFiredClass::*)(Timer<TimerFiredClass>*);
+    using TimerFiredFunction = typename TaskRunnerTimer<TimerFiredClass>::TimerFiredFunction;
 
-    ~UnthrottledTimer() override { }
+    ~UnthrottledThreadTimer() override { }
 
-    UnthrottledTimer(TimerFiredClass* timerFiredClass, TimerFiredFunction timerFiredFunction)
-        : Timer<TimerFiredClass>(timerFiredClass, timerFiredFunction, TimerBase::UnthrottledWebTaskRunner())
+    UnthrottledThreadTimer(TimerFiredClass* timerFiredClass, TimerFiredFunction timerFiredFunction)
+        : TaskRunnerTimer<TimerFiredClass>(TimerBase::getDefaultTaskRunner(), timerFiredClass, timerFiredFunction)
     {
     }
 };