Check whether the plugin is disabled in OnIsInternalPluginRegisteredForMimeType().

chrome/common/render_messages.h

Index: chrome/common/render_messages.h
diff --git a/chrome/common/render_messages.h b/chrome/common/render_messages.h
index 516f8a21fe9f54b6b56f3e6ef7ce9dbab74eda8f..eb4caab4a829c61ae49511b7ae2984b96f7a41f1 100644
--- a/chrome/common/render_messages.h
+++ b/chrome/common/render_messages.h
@@ -430,16 +430,16 @@ IPC_SYNC_MESSAGE_CONTROL4_1(ChromeViewHostMsg_GetPluginInfo,
                             ChromeViewHostMsg_GetPluginInfo_Output /* output */)
 
 #if defined(ENABLE_PEPPER_CDMS)
-// Returns whether any internal plugin supporting |mime_type| is registered
-// Does not determine whether the plugin can actually be instantiated
-// (e.g. whether it is allowed or has all its dependencies).
-// When the returned *|is_registered| is true, |additional_param_names| and
+// Returns whether any internal plugin supporting |mime_type| is registered and
+// enabled. Does not determine whether the plugin can actually be instantiated
+// (e.g. whether it has all its dependencies).
+// When the returned *|is_available| is true, |additional_param_names| and
 // |additional_param_values| contain the name-value pairs, if any, specified
-// for the *first* plugin found that is registered for |mime_type|.
+// for the *first* non-disabled plugin found that is registered for |mime_type|.
 IPC_SYNC_MESSAGE_CONTROL1_3(
-    ChromeViewHostMsg_IsInternalPluginRegisteredForMimeType,
+    ChromeViewHostMsg_IsInternalPluginAvailableForMimeType,
     std::string /* mime_type */,
-    bool /* registered */,
+    bool /* is_available */,
     std::vector<base::string16> /* additional_param_names */,
     std::vector<base::string16> /* additional_param_values */)
 #endif