Allow for pausing background tabs on desktop via about:flags.

chrome/common/pause_tabs_field_trial.h

Index: chrome/common/pause_tabs_field_trial.h
diff --git a/chrome/common/pause_tabs_field_trial.h b/chrome/common/pause_tabs_field_trial.h
new file mode 100644
index 0000000000000000000000000000000000000000..f98061159f55f2e7921113157d9bf8ed4bfdcf0c
--- /dev/null
+++ b/chrome/common/pause_tabs_field_trial.h
@@ -0,0 +1,26 @@
+// 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.
+
+#ifndef CHROME_COMMON_PAUSE_TABS_FIELD_TRIAL_H_
+#define CHROME_COMMON_PAUSE_TABS_FIELD_TRIAL_H_
+
+#include "base/feature_list.h"
+
+namespace pausetabs {
+
+const base::Feature kPauseBackgroundTabsFeature{
+    "PauseBackgroundTabs", base::FEATURE_DISABLED_BY_DEFAULT};
+
+const char kPauseBackgroundTabsFeatureParameterName[] = "pause-background-tabs";
+
+// Mode values.
+const char kPauseBackgroundTabsFeatureModeParameterMinimal[] = "minimal";
+const char kPauseBackgroundTabsFeatureModeParameterLow[] = "low";
+const char kPauseBackgroundTabsFeatureModeParameterMedium[] = "medium";
+const char kPauseBackgroundTabsFeatureModeParameterHigh[] = "high";
+const char kPauseBackgroundTabsFeatureModeParameterMax[] = "max";

[Alexei Svitkine (slow), 2017/04/10 20:44:49]

Nit: Given all of these already in pausetabs namespace, maybe names can be
shortened?

e.g. kModeParamMinimal, kModeParamLow, etc.

Same for the other ones. Even the feature could just be pausetabs::kFeature

+
+}  // namespace pausetabs
+
+#endif  // CHROME_COMMON_PAUSE_TABS_FIELD_TRIAL_H_