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

content/child/npapi/plugin_string_stream.cc

-// Copyright (c) 2010 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/plugin_string_stream.h"
-
-#include "url/gurl.h"
-
-namespace content {
-
-PluginStringStream::PluginStringStream(
-    PluginInstance* instance,
-    const GURL& url,
-    bool notify_needed,
-    void* notify_data)
-    : PluginStream(instance, url.spec().c_str(), notify_needed, notify_data) {
-}
-
-PluginStringStream::~PluginStringStream() {
-}
-
-void PluginStringStream::SendToPlugin(const std::string &data,
-                                      const std::string &mime_type) {
-  // Protect the stream against it being destroyed or the whole plugin instance
-  // being destroyed within the plugin stream callbacks.
-  scoped_refptr<PluginStringStream> protect(this);
-
-  int length = static_cast<int>(data.length());
-  if (Open(mime_type, std::string(), length, 0, false)) {
-    // TODO - check if it was not fully sent, and figure out a backup plan.
-    int written = Write(data.c_str(), length, 0);
-    NPReason reason = written == length ? NPRES_DONE : NPRES_NETWORK_ERR;
-    Close(reason);
-  }
-}
-
-}  // namespace content