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"
@@ skipping 23 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
   };
 
+  enum CachedValue {
+    NOT_CACHED,
+    CACHED_ENABLED,
+    CACHED_DISABLED
+  };
+
   // A temporary override for the switch value.
   class ScopedOverride {
    public:
     ScopedOverride(FeatureSwitch* feature, bool override_value);
     ~ScopedOverride();
    private:
     FeatureSwitch* feature_;
     FeatureSwitch::OverrideValue previous_value_;
     DISALLOW_COPY_AND_ASSIGN(ScopedOverride);
   };
@@ skipping 15 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 CachedValue cached_value_;

[Devlin, 2017/03/10 03:18:45]

nit: maybe use a base::Optional<bool> here?

[Kunihiko Sakamoto, 2017/03/10 07:07:28]

Done.

 
   DISALLOW_COPY_AND_ASSIGN(FeatureSwitch);
 };
 
 }  // namespace extensions
 
 #endif  // EXTENSIONS_COMMON_FEATURE_SWITCH_H_