Remove PluginLoadObserver and related logic, it was only used for NPAPI.

content/child/npapi/plugin_stream_url.h

Index: content/child/npapi/plugin_stream_url.h
diff --git a/content/child/npapi/plugin_stream_url.h b/content/child/npapi/plugin_stream_url.h
index dea2fe4d52ca717ee9d35c7da8d36c0e89c9b61b..27c0fae8ca4f6de162068c67aba401d8807b7783 100644
--- a/content/child/npapi/plugin_stream_url.h
+++ b/content/child/npapi/plugin_stream_url.h
@@ -21,14 +21,10 @@ class PluginStreamUrl : public PluginStream,
                         public WebPluginResourceClient {
  public:
   // Create a new stream for sending to the plugin by fetching
-  // a URL. If notifyNeeded is set, then the plugin will be notified
-  // when the stream has been fully sent to the plugin.  Initialize
-  // must be called before the object is used.
+  // a URL. Initialize must be called before the object is used.
   PluginStreamUrl(unsigned long resource_id,
                   const GURL &url,
-                  PluginInstance *instance,
-                  bool notify_needed,
-                  void *notify_data);
+                  PluginInstance *instance);
 
   void SetPluginURLFetcher(PluginURLFetcher* fetcher);