Experiment with more aggressive MSE GC on memory pressure

content/browser/renderer_host/render_view_host_impl.cc

 // Copyright (c) 2012 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 "content/browser/renderer_host/render_view_host_impl.h"
 
 #include <set>
 #include <string>
 #include <utility>
 #include <vector>
@@ skipping 532 matching lines @@
 
   // TODO(avayvod, asvitkine): Query the value directly when it is available in
   // the renderer process. See https://crbug.com/681160.
   prefs.max_keyframe_distance_to_disable_background_video =
       base::TimeDelta::FromMilliseconds(
           variations::GetVariationParamByFeatureAsInt(
               media::kBackgroundVideoTrackOptimization,
               "max_keyframe_distance_ms",
               base::TimeDelta::FromSeconds(10).InMilliseconds()));
 
+  // TODO(avayvod, asvitkine): Query the value directly when it is available in

[DaleCurtis, 2017/01/26 23:07:36]

TODO(servolk? :)

[servolk, 2017/01/27 00:52:13]

Done.

+  // the renderer process. See https://crbug.com/681160.
+  prefs.mse_force_gc_on_memory_pressure =
+      variations::GetVariationParamByFeatureAsBool(
+          media::kReduceMSEBuffersOnMemoryPressure,
+          "mse_force_gc_on_memory_pressure", false);

[DaleCurtis, 2017/01/26 23:07:36]

Not sure if we need two variations here or if the implicit split on true/false
is sufficient. Defer to the UMA folk.

[servolk, 2017/01/27 00:52:13]

We need to have at least 3 states:
1. No action on memory pressure (the old behavior and the control group for the
experiment).
2. More aggressive MSE GC, but delayed until the next SourceBuffer append.
3. More aggressive MSE GC that is forced to happen immediately on memory
pressure notification, without waiting for the next append.

+
   std::map<std::string, std::string> expensive_background_throttling_prefs;
   variations::GetVariationParamsByFeature(
       features::kExpensiveBackgroundTimerThrottling,
       &expensive_background_throttling_prefs);
   SetFloatParameterFromMap(expensive_background_throttling_prefs, "cpu_budget",
                            &prefs.expensive_background_throttling_cpu_budget);
   SetFloatParameterFromMap(
       expensive_background_throttling_prefs, "initial_budget",
       &prefs.expensive_background_throttling_initial_budget);
   SetFloatParameterFromMap(expensive_background_throttling_prefs, "max_budget",
@@ skipping 436 matching lines @@
   } else {
     render_view_ready_on_process_launch_ = true;
   }
 }
 
 void RenderViewHostImpl::RenderViewReady() {
   delegate_->RenderViewReady(this);
 }
 
 }  // namespace content