MD Settings: clarify "controlled by" logic

third_party/closure_compiler/interfaces/settings_private_interface.js

Index: third_party/closure_compiler/interfaces/settings_private_interface.js
diff --git a/third_party/closure_compiler/interfaces/settings_private_interface.js b/third_party/closure_compiler/interfaces/settings_private_interface.js
index dbbaa579996048520ac22e14a3750f04096f93db..be81e613c9acc5b9b8f20b11135d08c244980574 100644
--- a/third_party/closure_compiler/interfaces/settings_private_interface.js
+++ b/third_party/closure_compiler/interfaces/settings_private_interface.js
@@ -40,14 +40,16 @@ SettingsPrivate.prototype = {
   getPref: assertNotReached,
 
   /**
-   * Gets the page zoom factor.
+   * Gets the default page zoom factor. Possible values are currently between
+   * 0.25 and 5. For a full list, see zoom::kPresetZoomFactors.
    * @param {function(number):void} callback
    * @see https://developer.chrome.com/extensions/settingsPrivate#method-getDefaultZoom
    */
   getDefaultZoom: assertNotReached,
 
   /**
-   * Sets the page zoom factor.
+   * Sets the page zoom factor. Must be less than 0.001 different than a value
+   * in zoom::kPresetZoomFactors.
    * @param {number} zoom
    * @param {function(boolean):void=} callback
    * @see https://developer.chrome.com/extensions/settingsPrivate#method-setDefaultZoom