multibuffer field trial

media/blink/webmediaplayer_impl.cc

 // Copyright 2013 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 "media/blink/webmediaplayer_impl.h"
 
 #include <algorithm>
 #include <cmath>
 #include <limits>
 #include <string>
 #include <utility>
 
 #include "base/bind.h"
 #include "base/callback.h"
 #include "base/callback_helpers.h"
 #include "base/command_line.h"
 #include "base/debug/alias.h"
 #include "base/debug/crash_logging.h"
+#include "base/metrics/field_trial.h"
 #include "base/metrics/histogram.h"
 #include "base/single_thread_task_runner.h"
 #include "base/synchronization/waitable_event.h"
 #include "base/task_runner_util.h"
 #include "base/thread_task_runner_handle.h"
 #include "base/trace_event/trace_event.h"
 #include "build/build_config.h"
 #include "cc/blink/web_layer_impl.h"
 #include "cc/layers/video_layer.h"
 #include "gpu/blink/webgraphicscontext3d_impl.h"
@@ skipping 254 matching lines @@
   SetReadyState(WebMediaPlayer::ReadyStateHaveNothing);
   media_log_->AddEvent(media_log_->CreateLoadEvent(url.string().utf8()));
 
   // Media source pipelines can start immediately.
   if (load_type == LoadTypeMediaSource) {
     supports_save_ = false;
     StartPipeline();
     return;
   }
 
+  // TODO(hubbe): This experiment is temporary and should be removed once

[DaleCurtis, 2016/02/05 01:05:18]

I suspect the experiment folk are going to want you to turn this into a feature
flag instead of using the switches::kUseNewMediaCache. go/finch101 has the
details.

[hubbe, 2016/02/09 22:01:59]

Better now?

+  // we have enough data to support the primacy of the new media cache.
+  // See http://crbug.com/514719 for details.
+  //
+  // Note: It's important to query the field trial state first, to ensure that
+  // UMA reports the correct group.
+  const std::string group_name =
+      base::FieldTrialList::FindFullName("UseNewMediaCacheTrial");
+  const bool enabled_via_cli =
+      base::CommandLine::ForCurrentProcess()->HasSwitch(
+          switches::kUseNewMediaCache);
+  const bool use_multibuffer =
+      enabled_via_cli ||
+      base::StartsWith(group_name, "Enabled", base::CompareCase::SENSITIVE);
+
   // Otherwise it's a regular request which requires resolving the URL first.
-  if (base::CommandLine::ForCurrentProcess()->HasSwitch(
-          switches::kUseNewMediaCache)) {
+  if (use_multibuffer) {
     // Remove this when MultiBufferDataSource becomes default.
     LOG(WARNING) << "Using MultibufferDataSource";
     data_source_.reset(new MultibufferDataSource(
         url, static_cast<UrlData::CORSMode>(cors_mode), main_task_runner_,
         url_index_, frame_, media_log_.get(), &buffered_data_source_host_,
         base::Bind(&WebMediaPlayerImpl::NotifyDownloading, AsWeakPtr())));
   } else {
     data_source_.reset(new BufferedDataSource(
         url, static_cast<BufferedResourceLoader::CORSMode>(cors_mode),
         main_task_runner_, frame_, media_log_.get(),
@@ skipping 1243 matching lines @@
            << ", Video: " << stats.video_memory_usage << ", DataSource: "
            << (data_source_ ? data_source_->GetMemoryUsage() : 0)
            << ", Demuxer: " << demuxer_memory_usage;
 
   const int64_t delta = current_memory_usage - last_reported_memory_usage_;
   last_reported_memory_usage_ = current_memory_usage;
   adjust_allocated_memory_cb_.Run(delta);
 }
 
 }  // namespace media