Update the documentation: no longer needs to set clang_use_chrome_plugins

README.md

 # PDFium
 
 ## News
 
 As of 2016-05-04, GN is used to generate build files replacing GYP. GYP
 support will remain until it is disabled in Chromium and then will be removed
 from PDFium.
 
 As of 2016-04-28, the Visual Studio toolchain from depot_tools is used as the
 default Windows toolchain for Googlers. Please set DEPOT_TOOLS_WIN_TOOLCHAIN=0
@@ skipping 79 matching lines @@
 ```
 use_goma = true  # Googlers only.
 is_debug = true  # Enable debugging features.
 
 pdf_use_skia = false  # Set true to enable experimental skia backend.
 
 pdf_enable_xfa = true # Set false to remove XFA support (implies JS support).
 pdf_enable_v8 = true  # Set false to remove Javascript support.
 pdf_is_standalone = true  # Set for a non-embedded build.
 
-clang_use_chrome_plugins = false  # Currently must be false.
 ```
 
 Note, you must set `pdf_is_standalone = true` if you want the sample
 applications like `pdfium_test` to build.
 
 When complete the arguments will be stored in `<directory>/args.gn`.
 
 ## Building the code
 
 If you used Ninja, you can build the sample program by:
@@ skipping 47 matching lines @@
 and add the "Cr-Internals-Plugins-PDF" label.
 
 ## Contributing code
 
 For contributing code, we will follow
 [Chromium's process](http://dev.chromium.org/developers/contributing-code)
 as much as possible. The main exceptions is:
 
 1. Code has to conform to the existing style and not Chromium/Google style.