scheduler: Throttle timers in out-of-view frames

components/scheduler/renderer/web_frame_scheduler_impl.cc

 // 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.
 
 #include "components/scheduler/renderer/web_frame_scheduler_impl.h"
 
 #include "base/trace_event/blame_context.h"
 #include "components/scheduler/base/real_time_domain.h"
 #include "components/scheduler/base/virtual_time_domain.h"
 #include "components/scheduler/child/web_task_runner_impl.h"
 #include "components/scheduler/renderer/auto_advancing_virtual_time_domain.h"
 #include "components/scheduler/renderer/renderer_scheduler_impl.h"
 #include "components/scheduler/renderer/web_view_scheduler_impl.h"
 #include "third_party/WebKit/public/platform/BlameContext.h"
 #include "third_party/WebKit/public/platform/WebString.h"
 
 namespace scheduler {
 
 WebFrameSchedulerImpl::WebFrameSchedulerImpl(
     RendererSchedulerImpl* renderer_scheduler,
     WebViewSchedulerImpl* parent_web_view_scheduler,
-    base::trace_event::BlameContext* blame_context)
+    base::trace_event::BlameContext* blame_context,
+    bool allow_hidden_timer_throttling)
     : renderer_scheduler_(renderer_scheduler),
       parent_web_view_scheduler_(parent_web_view_scheduler),
       blame_context_(blame_context),
       frame_visible_(true),
-      page_visible_(true) {}
+      page_visible_(true),
+      cross_origin_(false),
+      allow_hidden_timer_throttling_(allow_hidden_timer_throttling) {}
 
 WebFrameSchedulerImpl::~WebFrameSchedulerImpl() {
   if (loading_task_queue_.get()) {
     loading_task_queue_->UnregisterTaskQueue();
     loading_task_queue_->SetBlameContext(nullptr);
   }
 
   if (timer_task_queue_.get()) {
     timer_task_queue_->UnregisterTaskQueue();
     timer_task_queue_->SetBlameContext(nullptr);
   }
 
   if (parent_web_view_scheduler_)
     parent_web_view_scheduler_->Unregister(this);
 }
 
 void WebFrameSchedulerImpl::DetachFromWebViewScheduler() {
   parent_web_view_scheduler_ = nullptr;
 }
 
 void WebFrameSchedulerImpl::setFrameVisible(bool frame_visible) {
+  DCHECK(parent_web_view_scheduler_);
+  if (frame_visible_ == frame_visible)
+    return;
+  bool was_throttled = ShouldThrottleTimers();
   frame_visible_ = frame_visible;
-  // TODO(alexclarke): Do something with this flag.
+  UpdateTimerThrottling(was_throttled);
+}
+
+void WebFrameSchedulerImpl::setCrossOrigin(bool cross_origin) {
+  DCHECK(parent_web_view_scheduler_);
+  if (cross_origin_ == cross_origin)
+    return;
+  bool was_throttled = ShouldThrottleTimers();
+  cross_origin_ = cross_origin;
+  UpdateTimerThrottling(was_throttled);
 }
 
 blink::WebTaskRunner* WebFrameSchedulerImpl::loadingTaskRunner() {
   DCHECK(parent_web_view_scheduler_);
   if (!loading_web_task_runner_) {
     loading_task_queue_ =
         renderer_scheduler_->NewLoadingTaskRunner("frame_loading_tq");
     loading_task_queue_->SetBlameContext(blame_context_);
     if (parent_web_view_scheduler_->virtual_time_domain()) {
       loading_task_queue_->SetTimeDomain(
           parent_web_view_scheduler_->virtual_time_domain());
     }
     loading_web_task_runner_.reset(new WebTaskRunnerImpl(loading_task_queue_));
   }
   return loading_web_task_runner_.get();
 }
 
 blink::WebTaskRunner* WebFrameSchedulerImpl::timerTaskRunner() {
   DCHECK(parent_web_view_scheduler_);
   if (!timer_web_task_runner_) {
     timer_task_queue_ =
         renderer_scheduler_->NewTimerTaskRunner("frame_timer_tq");
     timer_task_queue_->SetBlameContext(blame_context_);
     if (parent_web_view_scheduler_->virtual_time_domain()) {
       timer_task_queue_->SetTimeDomain(
           parent_web_view_scheduler_->virtual_time_domain());
-    } else if (!page_visible_) {
+    } else if (ShouldThrottleTimers()) {
       renderer_scheduler_->throttling_helper()->IncreaseThrottleRefCount(
           timer_task_queue_.get());
     }
     timer_web_task_runner_.reset(new WebTaskRunnerImpl(timer_task_queue_));
   }
   return timer_web_task_runner_.get();
 }
 
 void WebFrameSchedulerImpl::setPageVisible(bool page_visible) {
   DCHECK(parent_web_view_scheduler_);
   if (page_visible_ == page_visible)
     return;
-
+  bool was_throttled = ShouldThrottleTimers();
   page_visible_ = page_visible;
-
-  if (!timer_web_task_runner_ ||
-      parent_web_view_scheduler_->virtual_time_domain()) {
-    return;
-  }
-
-  if (page_visible_) {
-    renderer_scheduler_->throttling_helper()->DecreaseThrottleRefCount(
-        timer_task_queue_.get());
-  } else {
-    renderer_scheduler_->throttling_helper()->IncreaseThrottleRefCount(
-        timer_task_queue_.get());
-  }
+  UpdateTimerThrottling(was_throttled);
 }
 
 void WebFrameSchedulerImpl::OnVirtualTimeDomainChanged() {
   DCHECK(parent_web_view_scheduler_);
   DCHECK(parent_web_view_scheduler_->virtual_time_domain());
 
   if (timer_task_queue_) {
     renderer_scheduler_->throttling_helper()->UnregisterTaskQueue(
         timer_task_queue_.get());
     timer_task_queue_->SetTimeDomain(
         parent_web_view_scheduler_->virtual_time_domain());
   }
 
   if (loading_task_queue_) {
     loading_task_queue_->SetTimeDomain(
         parent_web_view_scheduler_->virtual_time_domain());
   }
 }
 
+bool WebFrameSchedulerImpl::ShouldThrottleTimers() const {
+  return !page_visible_ ||
+         (allow_hidden_timer_throttling_ && !frame_visible_ && cross_origin_);
+}
+
+void WebFrameSchedulerImpl::UpdateTimerThrottling(bool was_throttled) {
+  bool should_throttle = ShouldThrottleTimers();
+  if (was_throttled == should_throttle || !timer_web_task_runner_ ||
+      parent_web_view_scheduler_->virtual_time_domain()) {

[alex clarke (OOO till 29th), 2016/06/28 17:11:28]

This probably needs a comment explaining that we don't try to throttle a view
that has virtual time enabled.

[Sami, 2016/06/28 17:22:45]

Good point, done. (At some point we'll need to decide how throttling should
happen in headless mode.)

+    return;
+  }
+  if (should_throttle) {
+    renderer_scheduler_->throttling_helper()->IncreaseThrottleRefCount(
+        timer_task_queue_.get());
+  } else {
+    renderer_scheduler_->throttling_helper()->DecreaseThrottleRefCount(
+        timer_task_queue_.get());
+  }
+}
+
 }  // namespace scheduler