Fix the skinny, padded progress bar in the view source activity
Beginning in API 21 with the material theme, Google automatically uses a skinny, padded drawable for indeterminate horizontal progress bars. They make this very difficult to override.
Perhaps once API >= 21 this will be easier, because one will not have to reference `style="?android:attr/progressBarStyleHorizontal"` to select the correct progress bar style for pre and post material devices. At that point, perhaps `@android:drawable/progress_horizontal_material` will be accessible. Currently, only `@android:drawable/progress_horizontal` can be referenced.