Create --disable-extensions-except switch

chrome/browser/extensions/extension_service.h

Index: chrome/browser/extensions/extension_service.h
diff --git a/chrome/browser/extensions/extension_service.h b/chrome/browser/extensions/extension_service.h
index 0f1ea91ff6e8a66f91ce3a7ee1f4396547f1c94d..ef4e1ceabc8c80cc7265e936153c984fc5c7486b 100644
--- a/chrome/browser/extensions/extension_service.h
+++ b/chrome/browser/extensions/extension_service.h
@@ -458,6 +458,8 @@ class ExtensionService
   }
 
  private:
+  void LoadExtensionsFromCommandLineFlag(const char* switch_name);

[Devlin, 2016/08/30 14:15:39]

nit: We should add a function comment here describing the behavior.

+
   // Reloads the specified extension, sending the onLaunched() event to it if it
   // currently has any window showing. |be_noisy| determines whether noisy
   // failures are allowed for unpacked extension installs.
@@ -594,6 +596,8 @@ class ExtensionService
       const base::FilePath& install_dir,
       const base::FilePath& extension_path);
 
+  const base::CommandLine* command_line_ = nullptr;
+
   // The normal profile associated with this ExtensionService.
   Profile* profile_ = nullptr;
 
@@ -617,6 +621,10 @@ class ExtensionService
   // These extensions should appear in registry_.
   extensions::ExtensionSet greylist_;
 
+  // Set of whitelisted enabled extensions loaded from the
+  // --disable-extensions-except command line flag.
+  std::set<std::string> disable_flag_exempted_extensions_;
+
   // The list of extension installs delayed for various reasons.  The reason
   // for delayed install is stored in ExtensionPrefs. These are not part of
   // ExtensionRegistry because they are not yet installed.