Add a data source field for volumes.

chrome/test/data/extensions/api_test/file_browser/mount_test/test.js

Index: chrome/test/data/extensions/api_test/file_browser/mount_test/test.js
diff --git a/chrome/test/data/extensions/api_test/file_browser/mount_test/test.js b/chrome/test/data/extensions/api_test/file_browser/mount_test/test.js
index ff093636d55b3c93d5dd8916bff6fbb59a362093..459a280cec2215214584a6865b4240f1377136fe 100644
--- a/chrome/test/data/extensions/api_test/file_browser/mount_test/test.js
+++ b/chrome/test/data/extensions/api_test/file_browser/mount_test/test.js
@@ -7,6 +7,7 @@ var expectedVolume1 = {
   volumeId: 'removable:mount_path1',
   volumeLabel: 'mount_path1',
   sourcePath: 'device_path1',
+  volumeSource: 'device',
   volumeType: 'removable',
   deviceType: 'usb',
   devicePath: 'system_path_prefix1',
@@ -20,6 +21,7 @@ var expectedVolume2 = {
   volumeId: 'removable:mount_path2',
   volumeLabel: 'mount_path2',
   sourcePath: 'device_path2',
+  volumeSource: 'device',
   volumeType: 'removable',
   deviceType: 'mobile',
   devicePath: 'system_path_prefix2',
@@ -33,6 +35,7 @@ var expectedVolume3 = {
   volumeId: 'removable:mount_path3',
   volumeLabel: 'mount_path3',
   sourcePath: 'device_path3',
+  volumeSource: 'device',
   volumeType: 'removable',
   deviceType: 'optical',
   devicePath: 'system_path_prefix3',
@@ -45,6 +48,7 @@ var expectedVolume3 = {
 var expectedDownloadsVolume = {
   volumeId: /^downloads:Downloads[^\/]*$/,
   volumeLabel: '',
+  volumeSource: 'device',
   volumeType: 'downloads',
   isReadOnly: false,
   hasMedia: false,
@@ -55,6 +59,7 @@ var expectedDriveVolume = {
   volumeId: /^drive:drive[^\/]*$/,
   volumeLabel: '',
   sourcePath: /^\/special\/drive[^\/]*$/,
+  volumeSource: 'network',
   volumeType: 'drive',
   isReadOnly: false,
   hasMedia: false,
@@ -65,6 +70,7 @@ var expectedArchiveVolume = {
   volumeId: 'archive:archive_mount_path',
   volumeLabel: 'archive_mount_path',
   sourcePath: /removable\/mount_path3\/archive.zip$/,
+  volumeSource: 'file',
   volumeType: 'archive',
   isReadOnly: true,
   hasMedia: false,