[Presentation API] Remove references to presentation sessions.

content/public/common/presentation_info.cc

+// Copyright 2015 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/public/common/presentation_info.h"
+
+namespace content {
+
+PresentationInfo::PresentationInfo(const GURL& presentation_url,
+                                   const std::string& presentation_id)
+    : presentation_url(presentation_url), presentation_id(presentation_id) {}
+
+PresentationInfo::~PresentationInfo() {}
+
+PresentationError::PresentationError(PresentationErrorType error_type,
+                                     const std::string& message)
+    : error_type(error_type), message(message) {}
+
+PresentationError::~PresentationError() {}
+
+}  // namespace content