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

content/renderer/browser_plugin/browser_plugin.h

Index: content/renderer/browser_plugin/browser_plugin.h
diff --git a/content/renderer/browser_plugin/browser_plugin.h b/content/renderer/browser_plugin/browser_plugin.h
index 36793550e00747afb395e2973174d09c62b25886..c732ec2681c433bf110d809542315663aa604279 100644
--- a/content/renderer/browser_plugin/browser_plugin.h
+++ b/content/renderer/browser_plugin/browser_plugin.h
@@ -108,11 +108,6 @@ class CONTENT_EXPORT BrowserPlugin :
   void didReceiveData(const char* data, int data_length) override;
   void didFinishLoading() override;
   void didFailLoading(const blink::WebURLError& error) 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 executeEditCommand(const blink::WebString& name) override;
   bool executeEditCommand(const blink::WebString& name,
                           const blink::WebString& value) override;