Experiment with more aggressive MSE GC on memory pressure

media/base/media_switches.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 "build/build_config.h"
 #include "media/base/media_switches.h"
 #include "ppapi/features/features.h"
 
 namespace switches {
 
@@ skipping 146 matching lines @@
       base::FEATURE_ENABLED_BY_DEFAULT
 #else
       base::FEATURE_DISABLED_BY_DEFAULT
 #endif
 };
 
 // Let video track be unselected when video is playing in the background.
 const base::Feature kBackgroundVideoTrackOptimization{
     "BackgroundVideoTrackOptimization", base::FEATURE_DISABLED_BY_DEFAULT};
 
+// Reduce memory limits for MSE SourceBuffers under memory pressure conditions.

[DaleCurtis, 2017/01/26 19:24:50]

Probably would be easier to have a single feature with multiple values.

[servolk, 2017/01/26 19:38:31]

IIUC the base::Feature is only binary (enabled/disabled), I don't see a way to
use custom values in there. I guess we could use custom command-line param, but
I'm not sure if that's better than reusing the standard base::Feature and
base::Feature list functionality.

[DaleCurtis, 2017/01/26 19:48:33]

Sure it's binary only, but you can use variations to modify the feature,

https://cs.chromium.org/chromium/src/components/variations/variations_associa...

See an example of what we did for keyframe_distance here:
https://cs.chromium.org/search/?q=keyframe_distance

The key bit is this will allow you to do easier comparisons across your
experiment groups. You can't accurate compare the two groups otherwise.

+// This will relieve memory pressure by releasing stale data from MSE buffers.
+const base::Feature kReduceMSEBuffersOnMemoryPressure{
+    "ReduceMSEBuffersOnMemoryPressure", base::FEATURE_DISABLED_BY_DEFAULT};
+
+// Perform MSE garbage collection immediately when we get notification about
+// critical memory pressure, instead of waiting for the next SourceBuffer append
+// operation.
+const base::Feature kMSEInstantGCOnMemoryPressure{
+    "MSEInstantGCOnMemoryPressure", base::FEATURE_DISABLED_BY_DEFAULT};
+
 // Use shared block-based buffering for media.
 const base::Feature kUseNewMediaCache{"use-new-media-cache",
                                       base::FEATURE_ENABLED_BY_DEFAULT};
 
 // Correct video colors based on output display?
 const base::Feature kVideoColorManagement{"video-color-management",
                                           base::FEATURE_DISABLED_BY_DEFAULT};
 
 // Inform video blitter of video color space.
 const base::Feature kVideoBlitColorAccuracy{"video-blit-color-accuracy",
                                             base::FEATURE_DISABLED_BY_DEFAULT};
 
 // Enables support for External Clear Key (ECK) key system for testing on
 // supported platforms. On platforms that do not support ECK, this feature has
 // no effect.
 const base::Feature kExternalClearKeyForTesting{
     "external-clear-key-for-testing", base::FEATURE_DISABLED_BY_DEFAULT};
 
 #if defined(OS_ANDROID)
 // Replaces WPMA by the MediaPlayerRenderer for HLS and fallback playback.
 const base::Feature kAndroidMediaPlayerRenderer{
     "android-media-player-renderer", base::FEATURE_ENABLED_BY_DEFAULT};
 
 // Lock the screen orientation when a video goes fullscreen.
 const base::Feature kVideoFullscreenOrientationLock{
     "VideoFullscreenOrientationLock", base::FEATURE_ENABLED_BY_DEFAULT};
 #endif
 
 }  // namespace media