Add public API generation with cr.makePublic() and handle it in compiler pass

R=dbeam@chromium.org,tbreisacher@chromium.org
BUG=393873
TEST=third_party/closure_compiler/runner/how_to_test_compiler_pass.md

Review URL: https://codereview.chromium.org/557633002

Cr-Commit-Position: refs/heads/master@{#295173}

chrome/browser/resources/chromeos/login/oobe_screen_user_image.js

@@ -444,18 +444,14 @@ cr.define('login', function() {
   };
 
   // Forward public APIs to private implementations.
-  [
+  cr.makePublic(UserImageScreen, [
     'setDefaultImages',
     'setCameraPresent',
     'setProfilePictureEnabled',
     'setProfileImage',
     'setSelectedImage',
     'hideCurtain'
-  ].forEach(function(name) {
-    UserImageScreen[name] = function(value) {
-      $('user-image')[name + '_'](value);
-    };
-  });
+  ], $('user-image'));
 
   return {
     UserImageScreen: UserImageScreen

chrome/browser/resources/options/automatic_settings_reset_banner.js

@@ -12,6 +12,7 @@ cr.define('options', function() {
    * AutomaticSettingsResetBanner class
    * Provides encapsulated handling of the Reset Profile Settings banner.
    * @constructor
+   * @extends {options.SettingsBannerBase}
    */
   function AutomaticSettingsResetBanner() {}
 
@@ -47,18 +48,36 @@ cr.define('options', function() {
         PageManager.showPageByName('resetProfileSettings');
       };
     },
+
+    /**
+     * Called by the native code to show the banner if needed.
+     * @private
+     */
+    show_: function() {
+      if (!this.hadBeenDismissed_) {
+        chrome.send('metricsHandler:recordAction', [this.showMetricName_]);
+        this.setVisibility(true);
+      }
+    },
+
+    /**
+     * Called when the banner should be closed as a result of something taking
+     * place on the WebUI page, i.e. when its close button is pressed, or when
+     * the confirmation dialog for the profile settings reset feature is opened.
+     * @private
+     */
+    dismiss_: function() {
+      chrome.send(this.dismissNativeCallbackName_);
+      this.hadBeenDismissed_ = true;
+      this.setVisibility(false);
+    },
   };
 
   // Forward public APIs to private implementations.
-  [
+  cr.makePublic(AutomaticSettingsResetBanner, [
     'show',
     'dismiss',
-  ].forEach(function(name) {
-    AutomaticSettingsResetBanner[name] = function() {
-      var instance = AutomaticSettingsResetBanner.getInstance();
-      return instance[name + '_'].apply(instance, arguments);
-    };
-  });
+  ]);
 
   // Export
   return {

chrome/browser/resources/options/browser_options.js

@@ -17,10 +17,11 @@ cr.define('options', function() {
     DEFAULT: 1
   };
 
-  //
-  // BrowserOptions class
-  // Encapsulated handling of browser options page.
-  //
+  /**
+   * Encapsulated handling of browser options page.
+   * @constructor
+   * @extends {cr.ui.pageManager.Page}
+   */
   function BrowserOptions() {
     Page.call(this, 'settings', loadTimeData.getString('settingsTitle'),
               'settings');
@@ -736,7 +737,7 @@ cr.define('options', function() {
       section.classList.add('sliding');
 
       // Force a style recalc before starting the animation.
-      /** @suppress {uselessCode} */
+      /** @suppress {suspiciousCode} */
       section.offsetHeight;
 
       section.style.height = (showing ? container.offsetHeight : 0) + 'px';
@@ -1423,16 +1424,25 @@ cr.define('options', function() {
       ManageProfileOverlay.showDeleteDialog(this.getCurrentProfile_());
     },
 
+    /**
+     * @param {boolean} enabled
+     */
     setNativeThemeButtonEnabled_: function(enabled) {
       var button = $('themes-native-button');
       if (button)
         button.disabled = !enabled;
     },
 
+    /**
+     * @param {boolean} enabled
+     */
     setThemesResetButtonEnabled_: function(enabled) {
       $('themes-reset').disabled = !enabled;
     },
 
+    /**
+     * @param {boolean} managed
+     */
     setAccountPictureManaged_: function(managed) {
       var picture = $('account-picture');
       if (managed || UIAccountTweaks.loggedInAsGuest()) {
@@ -1464,6 +1474,9 @@ cr.define('options', function() {
       }
     },
 
+    /**
+     * @param {boolean} managed
+     */
     setWallpaperManaged_: function(managed) {
       var button = $('set-wallpaper');
       button.disabled = !!managed;
@@ -1915,7 +1928,7 @@ cr.define('options', function() {
   };
 
   //Forward public APIs to private implementations.
-  [
+  cr.makePublic(BrowserOptions, [
     'addBluetoothDevice',
     'deleteCurrentProfile',
     'enableCertificateButton',
@@ -1960,14 +1973,8 @@ cr.define('options', function() {
     'updateEasyUnlock',
     'updateManagesSupervisedUsers',
     'updateSearchEngines',
-    'updateStartupPages',
     'updateSyncState',
-  ].forEach(function(name) {
-    BrowserOptions[name] = function() {
-      var instance = BrowserOptions.getInstance();
-      return instance[name + '_'].apply(instance, arguments);
-    };
-  });
+  ]);
 
   if (cr.isChromeOS) {
     /**

chrome/browser/resources/options/chromeos/change_picture_options.js

@@ -324,19 +324,14 @@ cr.define('options', function() {
   };
 
   // Forward public APIs to private implementations.
-  [
+  cr.makePublic(ChangePictureOptions, [
     'closeOverlay',
     'setCameraPresent',
     'setDefaultImages',
     'setOldImage',
     'setProfileImage',
     'setSelectedImage',
-  ].forEach(function(name) {
-    ChangePictureOptions[name] = function() {
-      var instance = ChangePictureOptions.getInstance();
-      return instance[name + '_'].apply(instance, arguments);
-    };
-  });
+  ]);
 
   // Export
   return {

chrome/browser/resources/options/chromeos/keyboard_overlay.js

@@ -161,15 +161,10 @@ cr.define('options', function() {
   };
 
   // Forward public APIs to private implementations.
-  [
+  cr.makePublic(KeyboardOverlay, [
     'showCapsLockOptions',
     'showDiamondKeyOptions',
-  ].forEach(function(name) {
-    KeyboardOverlay[name] = function() {
-      var instance = KeyboardOverlay.getInstance();
-      return instance[name + '_'].apply(instance, arguments);
-    };
-  });
+  ]);
 
   // Export
   return {

chrome/browser/resources/options/manage_profile_overlay.js

@@ -356,7 +356,7 @@ cr.define('options', function() {
      * @param {boolean} nameIsUnique
      */
     getImportHandler_: function(supervisedUser, nameIsUnique) {
-      return (function() {
+      return function() {
         if (supervisedUser.needAvatar || !nameIsUnique) {
           PageManager.showPageByName('supervisedUserImport');
         } else {
@@ -366,7 +366,7 @@ cr.define('options', function() {
               [supervisedUser.name, supervisedUser.iconURL, false, true,
                    supervisedUser.id]);
         }
-      }).bind(this);
+      }.bind(this);
     },
 
     /**
@@ -597,7 +597,7 @@ cr.define('options', function() {
   };
 
   // Forward public APIs to private implementations.
-  [
+  cr.makePublic(ManageProfileOverlay, [
     'receiveDefaultProfileIconsAndNames',
     'receiveNewProfileDefaults',
     'receiveExistingProfileNames',
@@ -608,12 +608,7 @@ cr.define('options', function() {
     'showDeleteDialog',
     'showDisconnectManagedProfileDialog',
     'showCreateDialog',
-  ].forEach(function(name) {
-    ManageProfileOverlay[name] = function() {
-      var instance = ManageProfileOverlay.getInstance();
-      return instance[name + '_'].apply(instance, arguments);
-    };
-  });
+  ]);
 
   function CreateProfileOverlay() {
     Page.call(this, 'createProfile',
@@ -853,7 +848,7 @@ cr.define('options', function() {
   };
 
   // Forward public APIs to private implementations.
-  [
+  cr.makePublic(CreateProfileOverlay, [
     'cancelCreateProfile',
     'onError',
     'onSuccess',
@@ -861,12 +856,7 @@ cr.define('options', function() {
     'updateCreateInProgress',
     'updateSignedInStatus',
     'updateSupervisedUsersAllowed',
-  ].forEach(function(name) {
-    CreateProfileOverlay[name] = function() {
-      var instance = CreateProfileOverlay.getInstance();
-      return instance[name + '_'].apply(instance, arguments);
-    };
-  });
+  ]);
 
   // Export
   return {

chrome/browser/resources/options/password_manager.js

@@ -232,16 +232,11 @@ cr.define('options', function() {
   };
 
   // Forward public APIs to private implementations on the singleton instance.
-  [
+  cr.makePublic(PasswordManager, [
     'setSavedPasswordsList',
     'setPasswordExceptionsList',
     'showPassword'
-   ].forEach(function(name) {
-     PasswordManager[name] = function() {
-      var instance = PasswordManager.getInstance();
-      return instance[name + '_'].apply(instance, arguments);
-    };
-  });
+  ]);
 
   // Export
   return {

chrome/browser/resources/options/settings_banner.js

@@ -9,6 +9,7 @@ cr.define('options', function() {
 
   /**
    * Base class for banners that appear at the top of the settings page.
+   * @constructor
    */
   function SettingsBannerBase() {}
 
@@ -48,38 +49,14 @@ cr.define('options', function() {
      */
     setVisibilibyDomElement_: null,
 
-    /**
-     * Called by the native code to show the banner if needed.
-     * @private
-     */
-    show_: function() {
-      if (!this.hadBeenDismissed_) {
-        chrome.send('metricsHandler:recordAction', [this.showMetricName_]);
-        this.setVisibility_(true);
-      }
-    },
-
-    /**
-     * Called when the banner should be closed as a result of something taking
-     * place on the WebUI page, i.e. when its close button is pressed, or when
-     * the confirmation dialog for the profile settings reset feature is opened.
-     * @private
-     */
-    dismiss_: function() {
-      chrome.send(this.dismissNativeCallbackName_);
-      this.hadBeenDismissed_ = true;
-      this.setVisibility_(false);
-    },
-
     /**
      * Sets whether or not the reset profile settings banner shall be visible.
      * @param {boolean} show Whether or not to show the banner.
-     * @private
+     * @protected
      */
-    setVisibility_: function(show) {
+    setVisibility: function(show) {
       this.setVisibilibyDomElement_.hidden = !show;
     },
-
   };
 
   // Export

chrome/browser/resources/options/startup_overlay.js

@@ -155,15 +155,10 @@ cr.define('options', function() {
   };
 
   // Forward public APIs to private implementations.
-  [
+  cr.makePublic(StartupOverlay, [
     'updateStartupPages',
     'updateAutocompleteSuggestions',
-  ].forEach(function(name) {
-    StartupOverlay[name] = function() {
-      var instance = StartupOverlay.getInstance();
-      return instance[name + '_'].apply(instance, arguments);
-    };
-  });
+  ]);
 
   // Export
   return {

chrome/browser/resources/options/supervised_user_create_confirm.js

@@ -88,14 +88,9 @@ cr.define('options', function() {
   };
 
   // Forward public APIs to private implementations.
-  [
+  cr.makePublic(SupervisedUserCreateConfirmOverlay, [
     'setProfileInfo',
-  ].forEach(function(name) {
-    SupervisedUserCreateConfirmOverlay[name] = function() {
-      var instance = SupervisedUserCreateConfirmOverlay.getInstance();
-      return instance[name + '_'].apply(instance, arguments);
-    };
-  });
+  ]);
 
   // Export
   return {

chrome/browser/resources/options/supervised_user_import.js

@@ -236,14 +236,9 @@ cr.define('options', function() {
   };
 
   // Forward public APIs to private implementations.
-  [
+  cr.makePublic(SupervisedUserImportOverlay, [
     'onSuccess',
-  ].forEach(function(name) {
-    SupervisedUserImportOverlay[name] = function() {
-      var instance = SupervisedUserImportOverlay.getInstance();
-      return instance[name + '_'].apply(instance, arguments);
-    };
-  });
+  ]);
 
   // Export
   return {

chrome/browser/resources/options/supervised_user_list_data.js

@@ -134,19 +134,14 @@ cr.define('options', function() {
   };
 
   // Forward public APIs to private implementations.
-  [
+  cr.makePublic(SupervisedUserListData, [
     'addObserver',
     'onSigninError',
     'receiveExistingSupervisedUsers',
     'removeObserver',
     'requestExistingSupervisedUsers',
     'resetPromise',
-  ].forEach(function(name) {
-    SupervisedUserListData[name] = function() {
-      var instance = SupervisedUserListData.getInstance();
-      return instance[name + '_'].apply(instance, arguments);
-    };
-  });
+  ]);
 
   // Export
   return {

third_party/closure_compiler/README.chromium

@@ -19,7 +19,7 @@ Local modifications:
 - Chrome-specific coding conventions to understand cr.addSingletonGetter().
 - third_party/closure_compiler/runner/src/com/google/javascript/jscomp/ChromePass.java
   Added pass to handle namespace definition with cr.define(), object chain
-  creation with cr.exportPath() and property definition with
-  {cr|Object}.defineProperty().
+  creation with cr.exportPath(), property definition with
+  {cr|Object}.defineProperty() and public API generation with cr.makePublic().
   See third_party/closure_compiler/runner/how_to_test_compiler_pass.md for
   testing instructions on this pass.

third_party/closure_compiler/runner/src/com/google/javascript/jscomp/ChromePass.java

@@ -37,6 +37,7 @@ public class ChromePass extends AbstractPostOrderCallback implements CompilerPas
     private static final String CR_EXPORT_PATH = "cr.exportPath";
     private static final String OBJECT_DEFINE_PROPERTY = "Object.defineProperty";
     private static final String CR_DEFINE_PROPERTY = "cr.defineProperty";
+    private static final String CR_MAKE_PUBLIC = "cr.makePublic";
 
     private static final String CR_DEFINE_COMMON_EXPLANATION = "It should be called like this:"
             + " cr.define('name.space', function() '{ ... return {Export: Internal}; }');";
@@ -67,6 +68,19 @@ public class ChromePass extends AbstractPostOrderCallback implements CompilerPas
                     "Invalid cr.PropertyKind passed to cr.defineProperty(): expected ATTR,"
                     + " BOOL_ATTR or JS, found \"{0}\".");
 
+    static final DiagnosticType CR_MAKE_PUBLIC_HAS_NO_JSDOC =
+            DiagnosticType.error("JSC_CR_MAKE_PUBLIC_HAS_NO_JSDOC",
+                    "Private method exported by cr.makePublic() has no JSDoc.");
+
+    static final DiagnosticType CR_MAKE_PUBLIC_MISSED_DECLARATION =
+            DiagnosticType.error("JSC_CR_MAKE_PUBLIC_MISSED_DECLARATION",
+                    "Method \"{1}_\" exported by cr.makePublic() on \"{0}\" has no declaration.");
+
+    static final DiagnosticType CR_MAKE_PUBLIC_INVALID_SECOND_ARGUMENT =
+            DiagnosticType.error("JSC_CR_MAKE_PUBLIC_INVALID_SECOND_ARGUMENT",
+                    "Invalid second argument passed to cr.makePublic(): should be array of " +
+                    "strings.");
+
     public ChromePass(AbstractCompiler compiler) {
         this.compiler = compiler;
         // The global variable "cr" is declared in ui/webui/resources/js/cr.js.
@@ -92,6 +106,10 @@ public class ChromePass extends AbstractPostOrderCallback implements CompilerPas
                     callee.matchesQualifiedName(CR_DEFINE_PROPERTY)) {
                 visitPropertyDefinition(node, parent);
                 compiler.reportCodeChange();
+            } else if (callee.matchesQualifiedName(CR_MAKE_PUBLIC)) {
+                if (visitMakePublic(node, parent)) {
+                    compiler.reportCodeChange();
+                }
             }
         }
     }
@@ -140,6 +158,98 @@ public class ChromePass extends AbstractPostOrderCallback implements CompilerPas
         target.setJSDocInfo(builder.build(target));
     }
 
+    private boolean visitMakePublic(Node call, Node exprResult) {
+        boolean changesMade = false;
+        Node scope = exprResult.getParent();
+        String className = call.getChildAtIndex(1).getQualifiedName();
+        String prototype = className  + ".prototype";
+        Node methods = call.getChildAtIndex(2);
+
+        if (methods == null || !methods.isArrayLit()) {
+            compiler.report(JSError.make(exprResult, CR_MAKE_PUBLIC_INVALID_SECOND_ARGUMENT));
+            return changesMade;
+        }
+
+        Set<String> methodNames = new HashSet<>();
+        for (Node methodName: methods.children()) {
+            if (!methodName.isString()) {
+                compiler.report(JSError.make(methodName, CR_MAKE_PUBLIC_INVALID_SECOND_ARGUMENT));
+                return changesMade;
+            }
+            methodNames.add(methodName.getString());
+        }
+
+        for (Node child: scope.children()) {
+            if (isAssignmentToPrototype(child, prototype)) {
+                Node objectLit = child.getFirstChild().getChildAtIndex(1);
+                for (Node stringKey : objectLit.children()) {
+                    String field = stringKey.getString();
+                    changesMade |= maybeAddPublicDeclaration(field, methodNames, className,
+                                                             stringKey, scope, exprResult);
+                }
+            } else if (isAssignmentToPrototypeMethod(child, prototype)) {
+                Node assignNode = child.getFirstChild();
+                String qualifiedName = assignNode.getFirstChild().getQualifiedName();
+                String field = qualifiedName.substring(qualifiedName.lastIndexOf('.') + 1);
+                changesMade |= maybeAddPublicDeclaration(field, methodNames, className,
+                                                         assignNode, scope, exprResult);
+            } else if (isDummyPrototypeMethodDeclaration(child, prototype)) {
+                String qualifiedName = child.getFirstChild().getQualifiedName();
+                String field = qualifiedName.substring(qualifiedName.lastIndexOf('.') + 1);
+                changesMade |= maybeAddPublicDeclaration(field, methodNames, className,
+                                                         child.getFirstChild(), scope, exprResult);
+            }
+        }
+
+        for (String missedDeclaration : methodNames) {
+            compiler.report(JSError.make(exprResult, CR_MAKE_PUBLIC_MISSED_DECLARATION, className,
+                    missedDeclaration));
+        }
+
+        return changesMade;
+    }
+
+    private boolean isAssignmentToPrototype(Node node, String prototype) {
+        Node assignNode;
+        return node.isExprResult() && (assignNode = node.getFirstChild()).isAssign() &&
+                assignNode.getFirstChild().getQualifiedName().equals(prototype);
+    }
+
+    private boolean isAssignmentToPrototypeMethod(Node node, String prototype) {
+        Node assignNode;
+        return node.isExprResult() && (assignNode = node.getFirstChild()).isAssign() &&
+                assignNode.getFirstChild().getQualifiedName().startsWith(prototype + ".");
+    }
+
+    private boolean isDummyPrototypeMethodDeclaration(Node node, String prototype) {
+        Node getPropNode;
+        return node.isExprResult() && (getPropNode = node.getFirstChild()).isGetProp() &&
+                getPropNode.getQualifiedName().startsWith(prototype + ".");
+    }
+
+    private boolean maybeAddPublicDeclaration(String field, Set<String> publicAPIStrings,
+            String className, Node jsDocSourceNode, Node scope, Node exprResult) {
+        boolean changesMade = false;
+        if (field.endsWith("_")) {
+            String publicName = field.substring(0, field.length() - 1);
+            if (publicAPIStrings.contains(publicName)) {
+                Node methodDeclaration = NodeUtil.newQualifiedNameNode(
+                        compiler.getCodingConvention(), className + "." + publicName);
+                if (jsDocSourceNode.getJSDocInfo() != null) {
+                    methodDeclaration.setJSDocInfo(jsDocSourceNode.getJSDocInfo());
+                    scope.addChildBefore(
+                            IR.exprResult(methodDeclaration).srcrefTree(exprResult),
+                            exprResult);
+                    changesMade = true;
+                } else {
+                    compiler.report(JSError.make(jsDocSourceNode, CR_MAKE_PUBLIC_HAS_NO_JSDOC));
+                }
+                publicAPIStrings.remove(publicName);
+            }
+        }
+        return changesMade;
+    }
+
     private void visitExportPath(Node crExportPathNode, Node parent) {
         if (crExportPathNode.getChildCount() != 2) {
             compiler.report(JSError.make(crExportPathNode,
@@ -342,5 +452,4 @@ public class ChromePass extends AbstractPostOrderCallback implements CompilerPas
                     this.namespaceName + "." + externalName).srcrefTree(internalName);
         }
     }
-
 }

third_party/closure_compiler/runner/test/com/google/javascript/jscomp/ChromePassTest.java

@@ -363,4 +363,166 @@ public class ChromePassTest extends CompilerTestCase {
         test("cr.exportPath();", null, ChromePass.CR_EXPORT_PATH_WRONG_NUMBER_OF_ARGUMENTS);
     }
 
+    public void testCrMakePublicWorksOnOneMethodDefinedInPrototypeObject() throws Exception {
+        test(
+            "/** @constructor */\n" +
+            "function Class() {};\n" +
+            "\n" +
+            "Class.prototype = {\n" +
+            "  /** @return {number} */\n" +
+            "  method_: function() { return 42; }\n" +
+            "};\n" +
+            "\n" +
+            "cr.makePublic(Class, ['method']);",
+            "/** @constructor */\n" +
+            "function Class() {};\n" +
+            "\n" +
+            "Class.prototype = {\n" +
+            "  /** @return {number} */\n" +
+            "  method_: function() { return 42; }\n" +
+            "};\n" +
+            "\n" +
+            "/** @return {number} */\n" +
+            "Class.method;\n" +
+            "\n" +
+            "cr.makePublic(Class, ['method']);");
+    }
+
+    public void testCrMakePublicWorksOnTwoMethods() throws Exception {
+        test(
+            "/** @constructor */\n" +
+            "function Class() {}\n" +
+            "\n" +
+            "Class.prototype = {\n" +
+            "  /** @return {number} */\n" +
+            "  m1_: function() { return 42; },\n" +
+            "\n" +
+            "  /** @return {string} */\n" +
+            "  m2_: function() { return ''; }\n" +
+            "};\n" +
+            "\n" +
+            "cr.makePublic(Class, ['m1', 'm2']);",
+            "/** @constructor */\n" +
+            "function Class() {}\n" +
+            "\n" +
+            "Class.prototype = {\n" +
+            "  /** @return {number} */\n" +
+            "  m1_: function() { return 42; },\n" +
+            "\n" +
+            "  /** @return {string} */\n" +
+            "  m2_: function() { return ''; }\n" +
+            "}\n" +
+            "\n" +
+            "/** @return {number} */\n" +
+            "Class.m1;\n" +
+            "\n" +
+            "/** @return {string} */\n" +
+            "Class.m2;\n" +
+            "\n" +
+            "cr.makePublic(Class, ['m1', 'm2']);");
+    }
+
+    public void testCrMakePublicRequiresMethodsToHaveJSDoc() throws Exception {
+        test("/** @constructor */\n" +
+            "function Class() {}\n" +
+            "\n" +
+            "Class.prototype = {\n" +
+            "  method_: function() {}\n" +
+            "}\n" +
+            "\n" +
+            "cr.makePublic(Class, ['method']);", null, ChromePass.CR_MAKE_PUBLIC_HAS_NO_JSDOC);
+    }
+
+    public void testCrMakePublicDoesNothingWithMethodsNotInAPI() throws Exception {
+        test(
+            "/** @constructor */\n" +
+            "function Class() {}\n" +
+            "\n" +
+            "Class.prototype = {\n" +
+            "  method_: function() {}\n" +
+            "}\n" +
+            "\n" +
+            "cr.makePublic(Class, []);",
+            "/** @constructor */\n" +
+            "function Class() {}\n" +
+            "\n" +
+            "Class.prototype = {\n" +
+            "  method_: function() {}\n" +
+            "}\n" +
+            "\n" +
+            "cr.makePublic(Class, []);");
+    }
+
+    public void testCrMakePublicRequiresExportedMethodToBeDeclared() throws Exception {
+        test(
+            "/** @constructor */\n" +
+            "function Class() {}\n" +
+            "\n" +
+            "Class.prototype = {\n" +
+            "}\n" +
+            "\n" +
+            "cr.makePublic(Class, ['method']);", null,
+            ChromePass.CR_MAKE_PUBLIC_MISSED_DECLARATION);
+    }
+
+    public void testCrMakePublicWorksOnOneMethodDefinedDirectlyOnPrototype() throws Exception {
+        test(
+            "/** @constructor */\n" +
+            "function Class() {}\n" +
+            "\n" +
+            "/** @return {number} */\n" +
+            "Class.prototype.method_ = function() {};\n" +
+            "\n" +
+            "cr.makePublic(Class, ['method']);",
+            "/** @constructor */\n" +
+            "function Class() {}\n" +
+            "\n" +
+            "/** @return {number} */\n" +
+            "Class.prototype.method_ = function() {};\n" +
+            "\n" +
+            "/** @return {number} */\n" +
+            "Class.method;\n" +
+            "\n" +
+            "cr.makePublic(Class, ['method']);");
+    }
+
+    public void testCrMakePublicWorksOnDummyDeclaration() throws Exception {
+        test(
+            "/** @constructor */\n" +
+            "function Class() {}\n" +
+            "\n" +
+            "/** @return {number} */\n" +
+            "Class.prototype.method_;\n" +
+            "\n" +
+            "cr.makePublic(Class, ['method']);",
+            "/** @constructor */\n" +
+            "function Class() {}\n" +
+            "\n" +
+            "/** @return {number} */\n" +
+            "Class.prototype.method_;\n" +
+            "\n" +
+            "/** @return {number} */\n" +
+            "Class.method;\n" +
+            "\n" +
+            "cr.makePublic(Class, ['method']);");
+    }
+
+    public void testCrMakePublicReportsInvalidSecondArgumentMissing() throws Exception {
+        test(
+            "cr.makePublic(Class);", null,
+            ChromePass.CR_MAKE_PUBLIC_INVALID_SECOND_ARGUMENT);
+    }
+
+    public void testCrMakePublicReportsInvalidSecondArgumentNotAnArray() throws Exception {
+        test(
+            "cr.makePublic(Class, 42);", null,
+            ChromePass.CR_MAKE_PUBLIC_INVALID_SECOND_ARGUMENT);
+    }
+
+    public void testCrMakePublicReportsInvalidSecondArgumentArrayWithNotAString() throws Exception {
+        test(
+            "cr.makePublic(Class, [42]);", null,
+            ChromePass.CR_MAKE_PUBLIC_INVALID_SECOND_ARGUMENT);
+    }
+
 }

ui/webui/resources/js/cr.js

@@ -294,6 +294,23 @@ var cr = function() {
     };
   }
 
+  /**
+   * Forwards public APIs to private implementations.
+   * @param {Function} ctor Constructor that have private implementations in its
+   *     prototype.
+   * @param {Array.<string>} methods List of public method names that have their
+   *     underscored counterparts in constructor's prototype.
+   * @param {*=} opt_target Target node.
+   */
+  function makePublic(ctor, methods, opt_target) {
+    methods.forEach(function(method) {
+      ctor[method] = function() {
+        var target = opt_target || ctor.getInstance();
+        return target[method + '_'].apply(target, arguments);
+      };
+    });
+  }
+
   return {
     addSingletonGetter: addSingletonGetter,
     createUid: createUid,
@@ -303,6 +320,7 @@ var cr = function() {
     dispatchSimpleEvent: dispatchSimpleEvent,
     exportPath: exportPath,
     getUid: getUid,
+    makePublic: makePublic,
     PropertyKind: PropertyKind,
 
     get doc() {