Merge PluginGroups for Adobe Reader

      This patch introduces general support in PluginGroup for multiple version ranges with one minimum secure version each, to be used e.g. for multiple major versions currently supported by their manufacturer.

BUG=65207
TEST=test_shell_tests: PluginGroupTest*

Review URL: http://codereview.chromium.org/5621006

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@68726 0039d316-1c4b-4281-b951-d872f2087c98