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

content/child/npapi/webplugin_delegate_impl_win.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "content/child/npapi/webplugin_delegate_impl.h"
 
 #include <map>
 #include <set>
 #include <string>
 #include <vector>
 
 #include "base/bind.h"
 #include "base/compiler_specific.h"
 #include "base/lazy_instance.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/message_loop/message_loop.h"
 #include "base/strings/string_util.h"
 #include "base/strings/stringprintf.h"
 #include "base/synchronization/lock.h"
 #include "base/version.h"
 #include "base/win/iat_patch_function.h"
 #include "base/win/registry.h"
 #include "base/win/windows_version.h"
 #include "content/child/npapi/plugin_instance.h"
 #include "content/child/npapi/plugin_lib.h"
-#include "content/child/npapi/plugin_stream_url.h"
 #include "content/child/npapi/webplugin.h"
 #include "content/child/npapi/webplugin_ime_win.h"
 #include "content/common/cursors/webcursor.h"
 #include "content/common/plugin_constants_win.h"
 #include "content/public/common/content_constants.h"
 #include "skia/ext/platform_canvas.h"
 #include "third_party/WebKit/public/web/WebInputEvent.h"
 #include "ui/gfx/win/dpi.h"
 #include "ui/gfx/win/hwnd_util.h"
 
@@ skipping 1446 matching lines @@
     case WM_RBUTTONUP:
       ::ReleaseCapture();
       break;
 
     default:
       break;
   }
 }
 
 }  // namespace content