add "always allow" option to the mediastream infobar and allow user to allow/not allow acces to devi

chrome/common/pref_names.cc

Index: chrome/common/pref_names.cc
diff --git a/chrome/common/pref_names.cc b/chrome/common/pref_names.cc
index 8d1c35dee4b5dca0e2384bd527f2e78d8f690baf..ad01cddc0783b7173817d3b85907066cc6789ece 100644
--- a/chrome/common/pref_names.cc
+++ b/chrome/common/pref_names.cc
@@ -949,6 +949,7 @@ const char kGeolocationDefaultContentSetting[] =
 // Dictionary that maps [frame, toplevel] to their Geolocation content setting.
 const char kGeolocationContentSettings[] = "geolocation.content_settings";
 
+
 // Preference to disable 3D APIs (WebGL, Pepper 3D).
 const char kDisable3DAPIs[] = "disable_3d_apis";
 
@@ -1825,6 +1826,8 @@ const char kManagedDefaultGeolocationSetting[] =
     "profile.managed_default_content_settings.geolocation";
 const char kManagedDefaultNotificationsSetting[] =
     "profile.managed_default_content_settings.notifications";
+const char kManagedDefaultMediaStreamSetting[] =
+    "mediastream.default_content_settings";
 
 // Preferences that are exclusively used to store managed
 // content settings patterns.