Don't use command line flags for enabling the internal pdf plugin. Instead, ...

chrome/common/chrome_switches.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 "chrome/common/chrome_switches.h"
 
 #include "base/base_switches.h"
 #include "base/command_line.h"
 
 namespace switches {
@@ skipping 478 matching lines @@
 
 // Runs WebGL inside the renderer process.
 const char kInProcessWebGL[]                = "in-process-webgl";
 
 // Causes the browser to launch directly in incognito mode.
 const char kIncognito[]                     = "incognito";
 
 // Runs the Native Client inside the renderer process.
 const char kInternalNaCl[]                  = "internal-nacl";
 
-// Uses internal plugin for displaying PDFs.
-const char kInternalPDF[]                  = "internal-pdf";
-
 // Runs a trusted Pepper plugin inside the renderer process.
 const char kInternalPepper[]                = "internal-pepper";
 
 // Specifies the flags passed to JS engine
 const char kJavaScriptFlags[]               = "js-flags";
 
 // Load an extension from the specified directory.
 const char kLoadExtension[]                 = "load-extension";
 
 // Load an NPAPI plugin from the specified path.
@@ skipping 466 matching lines @@
 
 // -----------------------------------------------------------------------------
 // DO NOT ADD YOUR CRAP TO THE BOTTOM OF THIS FILE.
 //
 // You were going to just dump your switches here, weren't you? Instead,
 // please put them in alphabetical order above, or in order inside the
 // appropriate ifdef at the bottom. The order should match the header.
 // -----------------------------------------------------------------------------
 
 }  // namespace switches