[scheduler] Throttle background frames with 1% CPU limit

content/public/common/content_features.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 "build/build_config.h"
 #include "content/public/common/content_features.h"
 
 namespace features {
 
 // All features in alphabetical order.
@@ skipping 27 matching lines @@
 // --force-gpu-rasterization or --disable-gpu-rasterization.
 const base::Feature kDefaultEnableGpuRasterization{
     "DefaultEnableGpuRasterization", base::FEATURE_DISABLED_BY_DEFAULT};
 
 // Speculatively pre-evaluate Javascript which will likely use document.write to
 // load an external script. The feature extracts the written markup and sends it
 // to the preload scanner.
 const base::Feature kDocumentWriteEvaluator{"DocumentWriteEvaluator",
                                             base::FEATURE_DISABLED_BY_DEFAULT};
 
+// Throttle tasks in Blink background timer queues based on CPU budgets
+// for the background tab. Bug: https://crbug.com/639852.
+const base::Feature kExpensiveBackgroundTimerThrottling{
+    "ExpensiveBackgroundTimerThrottling", base::FEATURE_DISABLED_BY_DEFAULT};
+
 // Enables the Feature Policy framework for granting and removing access to
 // other features through HTTP headers.
 const base::Feature kFeaturePolicy{"FeaturePolicy",
                                    base::FEATURE_DISABLED_BY_DEFAULT};
 
 // Enables a blink::FontCache optimization that reuses a font to serve different
 // size of font.
 const base::Feature kFontCacheScaling{"FontCacheScaling",
                                       base::FEATURE_DISABLED_BY_DEFAULT};
 
@@ skipping 171 matching lines @@
 #endif
 
 #if defined(OS_WIN)
 // Emergency "off switch" for new Windows sandbox security mitigation,
 // sandbox::MITIGATION_EXTENSION_POINT_DISABLE.
 const base::Feature kWinSboxDisableExtensionPoints{
     "WinSboxDisableExtensionPoint", base::FEATURE_ENABLED_BY_DEFAULT};
 #endif
 
 }  // namespace features