In order to simplify m-c code, move some in pdf.js

 * move set/clear|Timeout/Interval and crackURL code in pdf.js
 * remove the "backdoor" in the proxy (used to dispatch event) and so return the dispatch function in the initializer
 * remove listeners if an error occured during sandbox initialization
 * add support for alert and prompt in the sandbox
 * add a function to eval in the global scope

gulpfile.js

@@ -374,7 +374,28 @@ function createScriptingBundle(defines, extraOptions = undefined) {
     .src("./src/pdf.scripting.js")
     .pipe(webpack2Stream(scriptingFileConfig))
     .pipe(replaceWebpackRequire())
-    .pipe(replaceJSRootName(scriptingAMDName, "pdfjsScripting"));
+    .pipe(
+      replace(
+        'root["' + scriptingAMDName + '"] = factory()',
+        "root.pdfjsScripting = factory()"
+      )
+    );
+}
+
+function createSandboxExternal(defines) {
+  const preprocessor2 = require("./external/builder/preprocessor2.js");
+  const licenseHeader = fs.readFileSync("./src/license_header.js").toString();
+
+  const ctx = {
+    saveComments: false,
+    defines,
+  };
+  return gulp.src("./src/pdf.sandbox.external.js").pipe(
+    transform("utf8", content => {
+      content = preprocessor2.preprocessPDFJSCode(ctx, content);
+      return `${licenseHeader}\n${content}`;
+    })
+  );
 }
 
 function createTemporaryScriptingBundle(defines, extraOptions = undefined) {
@@ -1203,6 +1224,9 @@ gulp.task(
       createScriptingBundle(defines).pipe(
         gulp.dest(MOZCENTRAL_CONTENT_DIR + "build")
       ),
+      createSandboxExternal(defines).pipe(
+        gulp.dest(MOZCENTRAL_CONTENT_DIR + "build")
+      ),
       createWorkerBundle(defines).pipe(
         gulp.dest(MOZCENTRAL_CONTENT_DIR + "build")
       ),
@@ -1791,7 +1815,7 @@ gulp.task(
 gulp.task("watch-dev-sandbox", function () {
   gulp.watch(
     [
-      "src/pdf.{sandbox,scripting}.js",
+      "src/pdf.{sandbox,sandbox.external,scripting}.js",
       "src/scripting_api/*.js",
       "src/shared/scripting_utils.js",
       "external/quickjs/*.js",

src/pdf.sandbox.external.js

@@ -0,0 +1,175 @@
+/* Copyright 2020 Mozilla Foundation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+// In mozilla-central, this file is loaded as non-module script,
+// so it mustn't have any dependencies.
+
+class SandboxSupportBase {
+  /**
+   * @param {DOMWindow} - win
+   */
+  constructor(win) {
+    this.win = win;
+    this.timeoutIds = new Map();
+
+    // Will be assigned after the sandbox is initialized
+    this.commFun = null;
+  }
+
+  destroy() {
+    this.commFunc = null;
+    this.timeoutIds.forEach(([_, id]) => this.win.clearTimeout(id));
+    this.timeoutIds = null;
+  }
+
+  /**
+   * @param {Object} val - Export a value in the sandbox.
+   */
+  exportValueToSandbox(val) {
+    throw new Error("Not implemented");
+  }
+
+  /**
+   * @param {Object} val - Import a value from the sandbox.
+   */
+  importValueFromSandbox(val) {
+    throw new Error("Not implemented");
+  }
+
+  /**
+   * @param {String} errorMessage - Create an error in the sandbox.
+   */
+  createErrorForSandbox(errorMessage) {
+    throw new Error("Not implemented");
+  }
+
+  /**
+   * @param {String} name - Name of the function to call in the sandbox
+   * @param {Array<Object>} args - Arguments of the function.
+   */
+  callSandboxFunction(name, args) {
+    try {
+      args = this.exportValueToSandbox(args);
+      this.commFun(name, args);
+    } catch (e) {
+      this.win.console.error(e);
+    }
+  }
+
+  createSandboxExternals() {
+    // All the functions in externals object are called
+    // from the sandbox.
+    const externals = {
+      setTimeout: (callbackId, nMilliseconds) => {
+        if (
+          typeof callbackId !== "number" ||
+          typeof nMilliseconds !== "number"
+        ) {
+          return;
+        }
+        const id = this.win.setTimeout(() => {
+          this.timeoutIds.delete(callbackId);
+          this.callSandboxFunction("timeoutCb", {
+            callbackId,
+            interval: false,
+          });
+        }, nMilliseconds);
+        this.timeoutIds.set(callbackId, id);
+      },
+      clearTimeout: id => {
+        this.win.clearTimeout(this.timeoutIds.get(id));
+        this.timeoutIds.delete(id);
+      },
+      setInterval: (callbackId, nMilliseconds) => {
+        if (
+          typeof callbackId !== "number" ||
+          typeof nMilliseconds !== "number"
+        ) {
+          return;
+        }
+        const id = this.win.setInterval(() => {
+          this.callSandboxFunction("timeoutCb", {
+            callbackId,
+            interval: true,
+          });
+        }, nMilliseconds);
+        this.timeoutIds.set(callbackId, id);
+      },
+      clearInterval: id => {
+        this.win.clearInterval(this.timeoutIds.get(id));
+        this.timeoutIds.delete(id);
+      },
+      alert: cMsg => {
+        if (typeof cMsg !== "string") {
+          return;
+        }
+        this.win.alert(cMsg);
+      },
+      prompt: (cQuestion, cDefault) => {
+        if (typeof cQuestion !== "string" || typeof cDefault !== "string") {
+          return null;
+        }
+        return this.win.prompt(cQuestion, cDefault);
+      },
+      parseURL: cUrl => {
+        const url = new this.win.URL(cUrl);
+        const props = [
+          "hash",
+          "host",
+          "hostname",
+          "href",
+          "origin",
+          "password",
+          "pathname",
+          "port",
+          "protocol",
+          "search",
+          "searchParams",
+          "username",
+        ];
+
+        return Object.fromEntries(
+          props.map(name => [name, url[name].toString()])
+        );
+      },
+      send: data => {
+        if (!data) {
+          return;
+        }
+        const event = new this.win.CustomEvent("updateFromSandbox", {
+          detail: this.importValueFromSandbox(data),
+        });
+        this.win.dispatchEvent(event);
+      },
+    };
+    Object.setPrototypeOf(externals, null);
+
+    return (name, args) => {
+      try {
+        const result = externals[name](...args);
+        return this.exportValueToSandbox(result);
+      } catch (error) {
+        throw this.createErrorForSandbox(error?.toString() ?? "");
+      }
+    };
+  }
+}
+
+if (typeof PDFJSDev === "undefined" || !PDFJSDev.test("MOZCENTRAL")) {
+  exports.SandboxSupportBase = SandboxSupportBase;
+} else {
+  /* eslint-disable-next-line no-unused-vars, no-var */
+  var EXPORTED_SYMBOLS = ["SandboxSupportBase"];
+}