Do not add mimetype to url as a query parameter

Bug: 11654127

Adding mimetype to url as a query parameter is a bad practice as
it requires us to inject app specific behavior to webview. There
also seems no reason to add this, so removing.

Change-Id: Ib2e5198981f2d37128ab545a33b83e8109bf3eef
(cherry picked from commit dd44be0b2e29ee043ac8c25dba34f11b9c018c46)
Merge tag 'android-4.4.3_r1' into HEAD

Android 4.4.3 release 1
Automatic translation import

Change-Id: I784a82152669a8385557cf74adc910a36b98ecac
Automatic translation import

Change-Id: If3bbbd370e54ded681a53d68bc45bd55dbca6eb4