[scheduler] Use Finch to control background throttling.

third_party/WebKit/public/platform/WebScheduler.h

 // 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.
 
 #ifndef WebScheduler_h
 #define WebScheduler_h
 
 #include "WebCommon.h"
 #include "WebString.h"
 #include "public/platform/WebThread.h"
 #include "public/platform/WebTraceLocation.h"
 #include "public/platform/WebViewScheduler.h"
 
 #include <memory>
 
 namespace blink {
-
 class WebTaskRunner;
-class WebView;
 
 // This class is used to submit tasks and pass other information from Blink to
 // the platform's scheduler.
 // TODO(skyostil): Replace this class with RendererScheduler.
 class BLINK_PLATFORM_EXPORT WebScheduler {
  public:
   class BLINK_PLATFORM_EXPORT InterventionReporter {
    public:
     virtual ~InterventionReporter() {}
 
     // The scheduler has performed an intervention, described by |message|,
     // which should be reported to the developer.
     virtual void ReportIntervention(const WebString& message) = 0;
   };
 
+  // Helper interface to plumb various settings from WebSettings to scheduler.
+  class BLINK_PLATFORM_EXPORT WebSchedulerSettings {

[Sami, 2016/11/04 16:50:28]

Instead of adding this generic interface, how would you feel about just adding a
configureBackgroundThrottling() method that takes all four parameters? The
reason I think I'd prefer that is that I don't want to introduce a new dumping
ground for settings but rather something more narrowly focused that we can blow
away once we're done with the Finch trials. WDYT?

[altimin, 2016/11/07 15:19:49]

Per offline discussion, renamed to WebViewSchedulerSettings and moved to
WebViewScheduler.

+   public:
+    virtual ~WebSchedulerSettings() {}
+
+    // Background throttling aggressiveness settings.
+    virtual float expensiveBackgroundThrottlingCPUBudget() = 0;
+    virtual float expensiveBackgroundThrottlingInitialBudget() = 0;
+    virtual float expensiveBackgroundThrottlingMaxBudget() = 0;
+    virtual float expensiveBackgroundThrottlingMaxDelay() = 0;
+  };
+
   virtual ~WebScheduler() {}
 
   // Called to prevent any more pending tasks from running. Must be called on
   // the associated WebThread.
   virtual void shutdown() = 0;
 
   // Returns true if there is high priority work pending on the associated
   // WebThread and the caller should yield to let the scheduler service that
   // work.  Must be called on the associated WebThread.
   virtual bool shouldYieldForHighPriorityWork() = 0;
@@ skipping 24 matching lines @@
 
   // Returns a WebTaskRunner for loading tasks. Can be called from any thread.
   virtual WebTaskRunner* loadingTaskRunner() = 0;
 
   // Returns a WebTaskRunner for timer tasks. Can be called from any thread.
   virtual WebTaskRunner* timerTaskRunner() = 0;
 
   // Creates a new WebViewScheduler for a given WebView. Must be called from
   // the associated WebThread.
   virtual std::unique_ptr<WebViewScheduler> createWebViewScheduler(
-      InterventionReporter*) = 0;
+      InterventionReporter*,
+      WebSchedulerSettings*) = 0;
 
   // Suspends the timer queue and increments the timer queue suspension count.
   // May only be called from the main thread.
   virtual void suspendTimerQueue() = 0;
 
   // Decrements the timer queue suspension count and re-enables the timer queue
   // if the suspension count is zero and the current scheduler policy allows it.
   virtual void resumeTimerQueue() = 0;
 
   enum class NavigatingFrameType { kMainFrame, kChildFrame };
@@ skipping 14 matching lines @@
 
   void postIdleTask(const WebTraceLocation&, std::unique_ptr<IdleTask>);
   void postNonNestableIdleTask(const WebTraceLocation&,
                                std::unique_ptr<IdleTask>);
 #endif
 };
 
 }  // namespace blink
 
 #endif  // WebScheduler_h