Split content script injections into multiple tasks

extensions/common/feature_switch.h

 // 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.
 
 #ifndef EXTENSIONS_COMMON_FEATURE_SWITCH_H_
 #define EXTENSIONS_COMMON_FEATURE_SWITCH_H_
 
 #include <string>
 
 #include "base/macros.h"
+#include "base/optional.h"
 
 namespace base {
 class CommandLine;
 }
 
 namespace extensions {
 
 // A switch that can turn a feature on or off. Typically controlled via
 // command-line switches but can be overridden, e.g., for testing.
 // Can also integrate with Finch's field trials.
@@ skipping 13 matching lines @@
   static FeatureSwitch* force_dev_mode_highlighting();
   static FeatureSwitch* prompt_for_external_extensions();
   static FeatureSwitch* error_console();
   static FeatureSwitch* enable_override_bookmarks_ui();
   static FeatureSwitch* extension_action_redesign();
   static FeatureSwitch* scripts_require_action();
   static FeatureSwitch* embedded_extension_options();
   static FeatureSwitch* trace_app_source();
   static FeatureSwitch* load_media_router_component_extension();
   static FeatureSwitch* native_crx_bindings();
+  static FeatureSwitch* yield_between_content_script_runs();
 
   enum DefaultValue {
     DEFAULT_ENABLED,
     DEFAULT_DISABLED
   };
 
   enum OverrideValue {
     OVERRIDE_NONE,
     OVERRIDE_ENABLED,
     OVERRIDE_DISABLED
@@ skipping 27 matching lines @@
 
   // Consider using ScopedOverride instead.
   void SetOverrideValue(OverrideValue value);
   OverrideValue GetOverrideValue() const;
 
   bool IsEnabled() const;
 
  private:
   std::string GetLegacyEnableFlag() const;
   std::string GetLegacyDisableFlag() const;
+  bool ComputeValue() const;
 
   const base::CommandLine* command_line_;
   const char* switch_name_;
   const char* field_trial_name_;
   bool default_value_;
   OverrideValue override_value_;
+  mutable base::Optional<bool> cached_value_;
 
   DISALLOW_COPY_AND_ASSIGN(FeatureSwitch);
 };
 
 }  // namespace extensions
 
 #endif  // EXTENSIONS_COMMON_FEATURE_SWITCH_H_