Give an app the file entries it had back on restart.

chrome/test/data/extensions/platform_apps/file_access_restored_test/test.js

Index: chrome/test/data/extensions/platform_apps/file_access_restored_test/test.js
diff --git a/chrome/test/data/extensions/platform_apps/file_access_restored_test/test.js b/chrome/test/data/extensions/platform_apps/file_access_restored_test/test.js
new file mode 100644
index 0000000000000000000000000000000000000000..07ebb0b4ca415d1ab22cda6790ed6a88d7403d0c
--- /dev/null
+++ b/chrome/test/data/extensions/platform_apps/file_access_restored_test/test.js
@@ -0,0 +1,74 @@
+// Copyright (c) 2012 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+var expectedText = 'def';
+
+function truncateAndWriteToFile(writableEntry, callback) {
+  writableEntry.createWriter(function(fileWriter) {
+    fileWriter.onerror = function(e) {
+      console.error("Couldn't write file: " + e.toString());
+    };
+    fileWriter.onwriteend = function(e) {
+      fileWriter.onwriteend = function(e) {
+        callback();
+      };
+      var blob = new Blob([expectedText], {type: 'text/plain'});
+      fileWriter.write(blob);
+    };
+    fileWriter.truncate(0);
+  });
+}
+
+chrome.app.runtime.onLaunched.addListener(function() {
+  chrome.app.window.create('index.html', {width: 100, height: 100},
+      function(win) {
+    var fs = win.contentWindow.chrome.fileSystem;
+    fs.chooseEntry({type: 'openFile'}, function(entry) {
+      fs.getWritableEntry(entry, function(writableEntry) {
+        var id = fs.getEntryId(entry);
+        chrome.storage.local.set({id:id}, function() {
+          truncateAndWriteToFile(writableEntry, function() {
+            chrome.test.sendMessage('fileWritten');
+            win.close();
+          });
+        });
+      });
+    });
+  });
+});
+
+chrome.app.runtime.onRestarted.addListener(function() {
+  chrome.storage.local.get(null, function(data) {
+    var entry = chrome.fileSystem.getEntryById(data.id);
+    if (!entry) {
+      console.error("couldn't get file entry " + data.id);
+      return;
+    }
+    entry.file(function(file) {
+      var fr = new FileReader();
+      fr.onload = function(e) {
+        if (e.target.result != expectedText) {
+          console.error(
+              "expected '" + expectedText + "', got '" + e.target.result + "'");
+          return;
+        }
+        entry.createWriter(function(fileWriter) {
+          fileWriter.onwriteend = function(e) {
+            chrome.test.sendMessage('restartedFileAccessOK');
+            win.close();
+          };
+          fileWriter.onerror = function(e) {
+            console.error('Write failed: ' + e.toString());
+          };
+          var blob = new Blob(["doesn't matter"], {type: 'text/plain'});
+          fileWriter.write(blob);
+        });
+      };
+      fr.onerror = function(e) {
+        chrome.test.fail("error reading file");
+      };
+      fr.readAsText(file);
+    });
+  });
+});