DevTools: Get rid of encoded and mimeType parameters in ContentProvider.requestContent() method.

R=pfeldman

Review URL: https://codereview.chromium.org/25460004

git-svn-id: svn://svn.chromium.org/blink/trunk@158799 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Remove reduntant call stack factories

BUG=None

Review URL: https://codereview.chromium.org/25714002

git-svn-id: svn://svn.chromium.org/blink/trunk@158800 bbb929c8-8fbe-4397-9dbb-9b2b20218538