[devtools] Support different encodings for Page.CaptureScreenshot.

testing/buildbot/gn_isolate_map.pyl

 ## Copyright 2015 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.
 
 # This is a .pyl, or "Python Literal", file. You can treat it just like a
 # .json file, with the following exceptions:
 # * all keys must be quoted (use single quotes, please);
 # * comments are allowed, using '#' syntax; and
 # * trailing commas are allowed.
 
@@ skipping 740 matching lines @@
     "type": "console_test_launcher",
   },
   "setup_unittests": {
     "label": "//chrome/installer/setup:setup_unittests",
     "type": "console_test_launcher",
   },
   "skia_unittests": {
     "label": "//skia:skia_unittests",
     "type": "console_test_launcher",
   },
+  "snapshot_unittests": {
+    "label": "//ui/snapshot:snapshot_unittests",
+    "type": "windowed_test_launcher",
+  },
   "sql_unittests": {
     "label": "//sql:sql_unittests",
     "type": "console_test_launcher",
   },
   "storage_unittests": {
     "label": "//storage/browser:storage_unittests",
     "type": "console_test_launcher",
   },
   "swiftshader_unittests": {
     "label": "//third_party/swiftshader/tests/unittests:swiftshader_unittests",
@@ skipping 220 matching lines @@
   },
   "wm_unittests": {
     "label": "//ui/wm:wm_unittests",
     "type": "windowed_test_launcher",
   },
   "wtf_unittests": {
     "label": "//third_party/WebKit/Source/wtf:wtf_unittests",
     "type": "console_test_launcher",
   },
 }