Change PlatformEventController to take LocalFrame rather than Page.

third_party/WebKit/Source/core/frame/PlatformEventController.cpp

 // Copyright 2014 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.
 
 #include "core/frame/PlatformEventController.h"
 
 #include "core/page/Page.h"
 
 namespace blink {
 
-PlatformEventController::PlatformEventController(Page* page)
-    : PageVisibilityObserver(page),
+PlatformEventController::PlatformEventController(LocalFrame* frame)

[dcheng, 2017/01/20 07:18:17]

Nit: I think this can be passed as mutable ref. Blink convention is to pass by
mutable reference as a signal that something should never be null.

[joelhockey, 2017/02/01 07:17:29]

Daniel, I must confess I don't know a lot of C++.  When I've searched about
mutable references, I only see talk about the mutable keyword for variable
declarations.  I don't think that is what you are talking about.

So are you saying to change
PlatformEventController::PlatformEventController(LocalFrame* frame)
to
PlatformEventController::PlatformEventController(LocalFrame &frame)
or something else?

+    : PageVisibilityObserver(frame->page()),
       m_hasEventListener(false),
       m_isActive(false),
       m_timer(this, &PlatformEventController::oneShotCallback) {}
 
 PlatformEventController::~PlatformEventController() {}
 
 void PlatformEventController::oneShotCallback(TimerBase* timer) {
   DCHECK_EQ(timer, &m_timer);
   ASSERT(hasLastData());
   ASSERT(!m_timer.isActive());
@@ skipping 27 matching lines @@
   if (!m_hasEventListener)
     return;
 
   if (page()->isPageVisible())
     startUpdating();
   else
     stopUpdating();
 }
 
 }  // namespace blink