WebUI: Serve mime type in Content-Type header

BUG=315513

Review URL: https://codereview.chromium.org/61783002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@233552 0039d316-1c4b-4281-b951-d872f2087c98
Move init of breakpad in the browser process as early as possible

On Linux and Android, we delayed initialization until the browser
process was already up. That way, certain crash keys did not get
registered correctly.

Instead, use a similar logic than on mac and windows to determine
whether we can run breakpad.

In particular, this relies on the fact that the GetCollectStatsConsent()
setting reflects the policy enforced value.

R=mark@chromium.org, pastarmovj@chromium.org, rsesek@chromium.org
BUG=311877

Review URL: https://codereview.chromium.org/61923002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@233553 0039d316-1c4b-4281-b951-d872f2087c98
Disabled startup sound.

BUG=271057
TEST=manual tests on Lumpy

Review URL: https://codereview.chromium.org/61813002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@233554 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 233554