Update Linux build docs to remove GYP references.

docs/linux_build_instructions.md

 # Linux-specific build instructions
 
 [TOC]
 
 ## Get the code
 
 [Get the Code](https://www.chromium.org/developers/how-tos/get-the-code). The
 general instructions on the "Get the code" page cover basic Linux build setup
 and configuration.
 
 This page documents some additional Linux-specific build issues.
 
 ## Overview
 
 Due its complexity, Chromium uses a set of custom tools to check out and build.
 Here's an overview of the steps you'll run:
 
 1.  **gclient**. A checkout involves pulling nearly 100 different SVN
     repositories of code. This process is managed with a tool called `gclient`.
-1.  **GN** / **gyp**. Cross-platform build configuration systems (GYP is the
-    older one, GN is the one being transitioned to). It generates ninja build
-    files. Running `gn`/`gyp` is analogous to the `./configure` step seen in
+1.  **GN**. Cross-platform build configuration system.  It generates ninja
+    build files. Running `gn` is analogous to the `./configure` step seen in
     most other software.
 1.  **ninja**. The actual build itself uses `ninja`. A prebuilt binary is in
     `depot_tools` and should already be in your path if you followed the steps
     to check out Chromium.
 1.  We don't provide any sort of "install" step.
 1.  You may want to
     [use a chroot](using_a_linux_chroot.md) to
     isolate yourself from versioning or packaging conflicts (or to run the
     layout tests).
 
 ## Getting a checkout
 
 [Prerequisites](linux_build_instructions_prerequisites.md): what you need before
 you build.
 
 **Note**. If you are working on Chromium OS and already have sources in
 `chromiumos/chromium`, you **must** run `chrome_set_ver --runhooks` to set the
 correct dependencies. This step is otherwise performed by `gclient` as part of
 your checkout.
 
 ## Compilation
 
-The weird "`src/`" directory is an artifact of `gclient`. Start with:
+The "`src/`" directory is an artifact of `gclient`. Start with:
 
     $ cd src
 
 ### Faster builds
 
 See [Linux Faster Builds](linux_faster_builds.md)
 
 ### Build every test
 
     $ ninja -C out/Debug
@@ skipping 26 matching lines @@
 If you want to see the actual commands that ninja is invoking, add `-v` to the
 ninja invocation.
 
     $ ninja -v -C out/Debug chrome
 
 This is useful if, for example, you are debugging gyp changes, or otherwise need
 to see what ninja is actually doing.
 
 ### Clean builds
 
-If you're using GN, you can clean the build directory (`out/Default` in this
-example):
+You can clean the build directory (`out/Default` in this example):
 
     gn clean out/Default
 
 This will delete all files except a bootstrap ninja file necessary for
 recreating the build.
 
-If you're using GYP, do:
-
-    rm -rf out
-    gclient runhooks
-
 Ninja can also be used to clean a build with `ninja -C out/Debug -t clean` but
 this will not be as complete as the above methods.
 
 ### Linker Crashes
 
 If, during the final link stage:
 
     LINK(target) out/Debug/chrome
 
 You get an error like:
@@ skipping 24 matching lines @@
 *   Want to use Eclipse as your IDE? See
     [LinuxEclipseDev](linux_eclipse_dev.md).
 *   Built version as Default Browser? See
     [LinuxDevBuildAsDefaultBrowser](linux_dev_build_as_default_browser.md).
 
 ## Next Steps
 
 If you want to contribute to the effort toward a Chromium-based browser for
 Linux, please check out the [Linux Development page](linux_development.md) for
 more information.