Unrevert: Show the install dialog for the initial load of an unpacked extension
with plugins.

First landing broke some browser tests.

BUG=83273
TEST=in the extensions managmenet page, with developer mode enabled, Load an unpacked extension on an extension with NPAPI plugins. You should get an install dialog.
TBR=mihaip

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@87738 0039d316-1c4b-4281-b951-d872f2087c98
static void ForceShutdownPlugin(const FilePath& plugin_path) {
  PluginProcessHost* plugin =
      PluginService::GetInstance()->FindNpapiPluginProcess(plugin_path);
  if (plugin)
     plugin->ForceShutdown();
 }

static void ForceShutdownPlugin(const FilePath& plugin_path) {
  PluginProcessHost* plugin =
      PluginService::GetInstance()->FindNpapiPluginProcess(plugin_path);
  if (plugin)
     plugin->ForceShutdown();
 }
