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

content/renderer/pepper/pepper_webplugin_impl.h

Index: content/renderer/pepper/pepper_webplugin_impl.h
diff --git a/content/renderer/pepper/pepper_webplugin_impl.h b/content/renderer/pepper/pepper_webplugin_impl.h
index 60464069c29f0407ed9a90becec60943fab628f6..5bfa9885c7425d965b65eacecb9d7d418247a5cf 100644
--- a/content/renderer/pepper/pepper_webplugin_impl.h
+++ b/content/renderer/pepper/pepper_webplugin_impl.h
@@ -62,11 +62,6 @@ class PepperWebPluginImpl : public blink::WebPlugin {
   void didReceiveData(const char* data, int data_length) override;
   void didFinishLoading() override;
   void didFailLoading(const blink::WebURLError&) override;
-  void didFinishLoadingFrameRequest(const blink::WebURL& url,
-                                    void* notify_data) override;
-  void didFailLoadingFrameRequest(const blink::WebURL& url,
-                                  void* notify_data,
-                                  const blink::WebURLError& error) override;
   bool hasSelection() const override;
   blink::WebString selectionAsText() const override;
   blink::WebString selectionAsMarkup() const override;