continue update even if user has deleted executable

editor/tools/plugins/com.google.dart.tools.update.core/src/com/google/dart/tools/update/core/internal/jobs/InstallUpdateAction.java

 /*
  * Copyright (c) 2012, the Dart project authors.
  * 
  * Licensed under the Eclipse Public License v1.0 (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.eclipse.org/legal/epl-v10.html
  * 
  * 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
@@ skipping 40 matching lines @@
 /**
  * An action that installs an available Dart Editor update.
  */
 public class InstallUpdateAction extends Action {
 
   /**
    * Internal representation of an executable file that needs to be renamed before update and
    * cleaned up after update.
    */
   private static class Executable {
+    static void add(List<Executable> list, String name, File executable) {
+      if (executable != null) {
+        list.add(new Executable(name, executable));
+      }
+    }
+
     private final String name;
     private final File executable;
     private final File oldExecutable;
 
     Executable(String name, File executable) {
       this.name = name;
       this.executable = executable;
       this.oldExecutable = new File(executable.getAbsolutePath() + ".old");
     }
 
     boolean deleteOld() {
       return !oldExecutable.exists() || oldExecutable.delete();
     }
 
     String getExistingProcessMessage() {
       return "Update complete, but existing " + name + " process still running.\n\n"
           + oldExecutable.getAbsolutePath();
     }
 
     String getRenameFailedMessage() {
       return "Could not update " + name + ". Please terminate any running\n" + name
           + " processes, check the file permissions, and try again.\n\n"
           + executable.getAbsolutePath() + "\n" + oldExecutable.getAbsolutePath();
     }
 
     boolean rename() {
-      return deleteOld() && executable.renameTo(oldExecutable);
+      return !executable.exists() || (deleteOld() && executable.renameTo(oldExecutable));
     }
 
     void restore() {
       oldExecutable.renameTo(executable);
     }
   }
 
   private static class RetryUpdateDialog extends MessageDialog {
 
     public RetryUpdateDialog(Shell parentShell) {
@@ skipping 82 matching lines @@
       if (!PlatformUI.getWorkbench().saveAllEditors(false)) {
         MessageDialog.openError(
             getShell(),
             UpdateJobMessages.InstallUpdateAction_errorTitle,
             UpdateJobMessages.InstallUpdateAction_error_in_save);
         return;
       }
     }
 
     DirectoryBasedDartSdk sdk = DartSdkManager.getManager().getSdk();
-    Executable[] executables = new Executable[] {
-        new Executable("Dart VM", sdk.getVmExecutable()),
-        new Executable("Dartium", sdk.getDartiumExecutable())};
+    List<Executable> executables = new ArrayList<Executable>();
+    Executable.add(executables, "Dart VM", sdk.getVmExecutable());
+    Executable.add(executables, "Dartium", sdk.getDartiumExecutable());
     int index = 0;
-    while (index < executables.length) {
-      if (!executables[index].rename()) {
-        Executable failedRename = executables[index];
+    while (index < executables.size()) {
+      if (!executables.get(index).rename()) {
+        Executable failedRename = executables.get(index);
         --index;
         while (index >= 0) {
-          executables[index].restore();
+          executables.get(index).restore();
           --index;
         }
         MessageDialog.openError(
             getShell(),
             UpdateJobMessages.InstallUpdateAction_errorTitle,
             failedRename.getRenameFailedMessage());
         return;
       }
       ++index;
     }
@@ skipping 320 matching lines @@
   private void terminateRunningDartLaunches() {
     ILaunchManager launchManager = DebugPlugin.getDefault().getLaunchManager();
     for (ILaunch launch : launchManager.getLaunches()) {
       if (!launch.isTerminated() && isDartLaunch(launch) && launch.canTerminate()) {
         terminate(launch);
       }
     }
   }
 
 }