[Android] Make cmdline_file argument to FlagChanger mandatory.

We shouldn't be setting that file for apps with no command line file.

BUG=None
NOTRY=True

Review URL: https://codereview.chromium.org/107113006

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@242933 0039d316-1c4b-4281-b951-d872f2087c98
Record PLT in UMA for previewed pages.

This will be used to measure the impact of showing preview for search
results.

BUG=

Review URL: https://codereview.chromium.org/109793007

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@242934 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 242934
reviewed incorrect snippets and updated serial api doc

BUG=330850

Review URL: https://codereview.chromium.org/118273006

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@242935 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 242935
When stopping QTKit video capture, call stopRunning before removeInput:.

Empirically, this prevents a browser hang when the active camera is
unplugged.  The unplug event triggers both stopping the capturer and
enumerating the available input devices at the same time.  It seems
that calling removeInput: on a running capturer after an error
produces a deadlock, but stopping the capturer first resolves the
problem.

BUG=285053

Review URL: https://codereview.chromium.org/120963003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@242936 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 242936