Filter run loop modes in message_pump_mac.mm

There's a non-trivial overhead for the machinery to run posted tasks in
a given run loop mode. Only observe modes known to be run for a particular
thread.

BUG=640466, 724076

Review-Url: https://codereview.chromium.org/2889293002
Cr-Commit-Position: refs/heads/master@{#473391}

base/message_loop/message_pump_mac.h

@@ -79,26 +79,29 @@ typedef NSAutoreleasePool AutoreleasePoolType;
 #endif  // !defined(__OBJC__) || __has_feature(objc_arc)
 
 class BASE_EXPORT MessagePumpCFRunLoopBase : public MessagePump {
+ public:
+  // MessagePump:
+  void Run(Delegate* delegate) override;
+  void ScheduleWork() override;
+  void ScheduleDelayedWork(const TimeTicks& delayed_work_time) override;
+  void SetTimerSlack(TimerSlack timer_slack) override;
+
+ protected:
   // Needs access to CreateAutoreleasePool.
   friend class MessagePumpScopedAutoreleasePool;
   friend class TestMessagePumpCFRunLoopBase;
 
- public:
-  MessagePumpCFRunLoopBase();
+  // Tasks will be pumped in the run loop modes described by |mode_mask|, which
+  // maps bits to the index of an internal array of run loop mode identifiers.
+  explicit MessagePumpCFRunLoopBase(int mode_mask);
   ~MessagePumpCFRunLoopBase() override;
 
   // Subclasses should implement the work they need to do in MessagePump::Run
   // in the DoRun method.  MessagePumpCFRunLoopBase::Run calls DoRun directly.
   // This arrangement is used because MessagePumpCFRunLoopBase needs to set
   // up and tear down things before and after the "meat" of DoRun.
-  void Run(Delegate* delegate) override;
   virtual void DoRun(Delegate* delegate) = 0;
 
-  void ScheduleWork() override;
-  void ScheduleDelayedWork(const TimeTicks& delayed_work_time) override;
-  void SetTimerSlack(TimerSlack timer_slack) override;
-
- protected:
   // Accessors for private data members to be used by subclasses.
   CFRunLoopRef run_loop() const { return run_loop_; }
   int nesting_level() const { return nesting_level_; }
@@ -114,6 +117,11 @@ class BASE_EXPORT MessagePumpCFRunLoopBase : public MessagePump {
   // objects autoreleased by work to fall into the current autorelease pool.
   virtual AutoreleasePoolType* CreateAutoreleasePool();
 
+  // Invokes function(run_loop_, arg, mode) for all the modes in |mode_mask_|.
+  template <typename Argument>
+  void InvokeForEnabledModes(void function(CFRunLoopRef, Argument, CFStringRef),
+                             Argument argument);
+
  private:
   // Marking timers as invalid at the right time helps significantly reduce
   // power use (see the comment in RunDelayedWorkTimer()), however there is no
@@ -190,6 +198,9 @@ class BASE_EXPORT MessagePumpCFRunLoopBase : public MessagePump {
   // The thread's run loop.
   CFRunLoopRef run_loop_;
 
+  // Bitmask controlling the run loop modes in which posted tasks may run.
+  const int mode_mask_;
+
   // The timer, sources, and observers are described above alongside their
   // callbacks.
   CFRunLoopTimerRef delayed_work_timer_;