Stop forcing optional permission on usbDevices section

chrome/common/extensions/permissions/api_permission.h

Index: chrome/common/extensions/permissions/api_permission.h
diff --git a/chrome/common/extensions/permissions/api_permission.h b/chrome/common/extensions/permissions/api_permission.h
index 5edc40c919d32f972bef09d57567ca3b1058b311..c8777d8f2f53b7370991af92ce6dacf696f766fb 100644
--- a/chrome/common/extensions/permissions/api_permission.h
+++ b/chrome/common/extensions/permissions/api_permission.h
@@ -221,10 +221,7 @@ class APIPermissionInfo {
     kFlagImpliesFullURLAccess = 1 << 1,
 
     // Indicates that extensions cannot specify the permission as optional.
-    kFlagCannotBeOptional = 1 << 3,
-
-    // Indicates that extensions must specify the permission as optional.
-    kFlagMustBeOptional = 1 << 4
+    kFlagCannotBeOptional = 1 << 3
   };
 
   typedef APIPermission* (*APIPermissionConstructor)(const APIPermissionInfo*);
@@ -264,12 +261,6 @@ class APIPermissionInfo {
     return (flags_ & kFlagCannotBeOptional) == 0;
   }
 
-  // Returns true if this permission must be added and removed via the
-  // optional permissions extension API.
-  bool must_be_optional() const {
-    return (flags_ & kFlagMustBeOptional) != 0;
-  }
-
  private:
   // Instances should only be constructed from within a
   // PermissionsInfo::Delegate.