WidevineCdmComponentInstaller: Purges plugin list cache after plugin registration.

Without PurgePluginListCache(), the plugin list info in existing renderer processes
is not updated. User has to close the original tab and open a new tab to be able to
load the plugin.

BUG=394988
TEST=CDM loaded after refreshing tab after CDM update now.

Review URL: https://codereview.chromium.org/400273002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@284606 0039d316-1c4b-4281-b951-d872f2087c98

chrome/browser/component_updater/widevine_cdm_component_installer.cc

@@ -220,7 +220,10 @@ void RegisterWidevineCdmWithChrome(const base::Version& cdm_version,
   // true = Add to beginning of list to override any existing registrations.
   PluginService::GetInstance()->RegisterInternalPlugin(
       plugin_info.ToWebPluginInfo(), true);
+  // Tell the browser to refresh the plugin list. Then tell all renderers to
+  // update their plugin list caches.
   PluginService::GetInstance()->RefreshPlugins();
+  PluginService::GetInstance()->PurgePluginListCache(NULL, false);
 }
 
 }  // namespace