Docserver: Split out the template rendering logic from TemplateDataSource into
a separate TemplateRender class and pull TemplateDataSource construction into
the DataSourceRegistry.

BUG=293678
R=jyasskin@chromium.org

Review URL: https://codereview.chromium.org/40723002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@232177 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 232177
We want to know which dangerous file types are causing the DANGEROUS_FILE warnings. This CL adds three new UMA histograms to track the relative frequencies of the "dangerous" file types.

BUG=269085

Review URL: https://codereview.chromium.org/50703012

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@232178 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 232178