Experiment with more aggressive MSE GC on memory pressure

media/blink/webmediaplayer_impl.cc

Index: media/blink/webmediaplayer_impl.cc
diff --git a/media/blink/webmediaplayer_impl.cc b/media/blink/webmediaplayer_impl.cc
index 0ab7b54d2cfdf4ee3dc09c257d782eea66e0c312..faedac99742e7f609ad8eea2cf4cd3248c84fdc1 100644
--- a/media/blink/webmediaplayer_impl.cc
+++ b/media/blink/webmediaplayer_impl.cc
@@ -18,6 +18,7 @@
 #include "base/debug/alias.h"
 #include "base/debug/crash_logging.h"
 #include "base/location.h"
+#include "base/memory/ptr_util.h"
 #include "base/metrics/histogram_macros.h"
 #include "base/single_thread_task_runner.h"
 #include "base/strings/string_number_conversions.h"
@@ -1168,6 +1169,22 @@ void WebMediaPlayerImpl::OnDemuxerOpened() {
       new WebMediaSourceImpl(chunk_demuxer_, media_log_));
 }
 
+void WebMediaPlayerImpl::OnMemoryPressure(
+    base::MemoryPressureListener::MemoryPressureLevel memory_pressure_level) {
+  DVLOG(2) << __func__ << " memory_pressure_level=" << memory_pressure_level;
+  DCHECK(main_task_runner_->BelongsToCurrentThread());
+  DCHECK(base::FeatureList::IsEnabled(kReduceMSEBuffersOnMemoryPressure));

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

Seems this should include both features?

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

No, the kMSEInstantGCOnMemoryPressure may or may not be enabled here. If
kMSEInstantGCOnMemoryPressure is enabled, then we'll perform GC immediately
within this call. If kMSEInstantGCOnMemoryPressure is disabled, then we'll just
remember the memory pressure state in the SourceBufferStream and that'll take
effect on the next append operation.

+  if (chunk_demuxer_) {
+    // base::Unretained is safe, since chunk_demuxer_ is actually owned by
+    // |this| via this->demuxer_.
+    media_task_runner_->PostTask(
+        FROM_HERE, base::Bind(&ChunkDemuxer::OnMemoryPressure,
+                              base::Unretained(chunk_demuxer_),
+                              base::TimeDelta::FromSecondsD(currentTime()),
+                              memory_pressure_level));
+  }
+}
+
 void WebMediaPlayerImpl::OnError(PipelineStatus status) {
   DVLOG(1) << __func__;
   DCHECK(main_task_runner_->BelongsToCurrentThread());
@@ -1717,6 +1734,13 @@ void WebMediaPlayerImpl::StartPipeline() {
         BIND_TO_RENDER_LOOP(&WebMediaPlayerImpl::OnDemuxerOpened),
         encrypted_media_init_data_cb, media_log_);
     demuxer_.reset(chunk_demuxer_);
+
+    if (base::FeatureList::IsEnabled(kReduceMSEBuffersOnMemoryPressure)) {
+      // base::Unretained is safe because |this| owns memory_pressure_listener_.
+      memory_pressure_listener_ =
+          base::MakeUnique<base::MemoryPressureListener>(base::Bind(
+              &WebMediaPlayerImpl::OnMemoryPressure, base::Unretained(this)));
+    }
   }
 
   // TODO(sandersd): FileSystem objects may also be non-static, but due to our