[scheduler] Fix --disable-background-timer-throttling flag.

third_party/WebKit/Source/platform/scheduler/renderer/renderer_scheduler_impl.cc

 // 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 "platform/scheduler/renderer/renderer_scheduler_impl.h"
 
 #include "base/bind.h"
 #include "base/debug/stack_trace.h"
 #include "base/logging.h"
 #include "base/memory/ptr_util.h"
@@ skipping 1154 matching lines @@
     new_policy.loading_queue_policy.time_domain_type = TimeDomainType::VIRTUAL;
     new_policy.timer_queue_policy.time_domain_type = TimeDomainType::VIRTUAL;
   }
 
   new_policy.should_disable_throttling =
       ShouldDisableThrottlingBecauseOfAudio(now) ||
       GetMainThreadOnly().use_virtual_time;
 
   // TODO(altimin): Consider adding default timer tq to background time
   // budget pool.
-  if (GetMainThreadOnly().renderer_backgrounded)
+  if (GetMainThreadOnly().renderer_backgrounded &&
+      RuntimeEnabledFeatures::timerThrottlingForBackgroundTabsEnabled()) {
     new_policy.timer_queue_policy.time_domain_type = TimeDomainType::THROTTLED;
+  }
 
   // Tracing is done before the early out check, because it's quite possible we
   // will otherwise miss this information in traces.
   CreateTraceEventObjectSnapshotLocked();
   TRACE_COUNTER1(TRACE_DISABLED_BY_DEFAULT("renderer.scheduler"), "use_case",
                  use_case);
   TRACE_COUNTER1(TRACE_DISABLED_BY_DEFAULT("renderer.scheduler"), "rail_mode",
                  new_policy.rail_mode);
   TRACE_COUNTER1(TRACE_DISABLED_BY_DEFAULT("renderer.scheduler"),
                  "touchstart_expected_soon",
@@ skipping 867 matching lines @@
     case TimeDomainType::VIRTUAL:
       return "virtual";
     default:
       NOTREACHED();
       return nullptr;
   }
 }
 
 }  // namespace scheduler
 }  // namespace blink