Add Beta Forum experiment to fieldtrial_testing_config.json.

Also fixed formatting script to not output \r\n on Windows.

Bug: 706105
Change-Id: I69f8f9c39cbf72d6d568ed2689244d96488fdb0c
Reviewed-on: https://chromium-review.googlesource.com/576410
Commit-Queue: Bret Sepulveda <bsep@chromium.org>
Reviewed-by: Robert Kaplow <rkaplow@chromium.org>
Cr-Commit-Position: refs/heads/master@{#488422}

testing/variations/PRESUBMIT.py

@@ -239,7 +239,7 @@ def CheckChangeOnCommit(input_api, output_api):
 def main(argv):
   content = open(argv[1]).read()
   pretty = PrettyPrint(content)
-  open(argv[1],'w').write(pretty)
+  open(argv[1], 'wb').write(pretty)
 
 if __name__ == "__main__":
   sys.exit(main(sys.argv))

testing/variations/fieldtrial_testing_config.json

@@ -1350,6 +1350,24 @@
             ]
         }
     ],
+    "IncludeBetaForumMenuItem": [
+        {
+            "platforms": [
+                "chromeos",
+                "linux",
+                "mac",
+                "win"
+            ],
+            "experiments": [
+                {
+                    "name": "Enabled",
+                    "enable_features": [
+                        "IncludeBetaForumMenuItem"
+                    ]
+                }
+            ]
+        }
+    ],
     "IncognitoWindowPromo": [
         {
             "platforms": [