Update Linux build docs to remove GYP references.

docs/linux_debugging.md

 # Tips for debugging on Linux
 
 This page is for Chromium-specific debugging tips; learning how to run gdb is
 out of scope.
 
 [TOC]
 
 ## Symbolized stack trace
 
 The sandbox can interfere with the internal symbolizer. Use `--no-sandbox` (but
@@ skipping 252 matching lines @@
 `build/gdb-add-index out/Debug/browser_tests`)
 
 Only makes sense if you run the binary multiple times or maybe if you use the
 component build since most `.so` files won't require reindexing on a rebuild.
 
 See
 https://groups.google.com/a/chromium.org/forum/#!searchin/chromium-dev/gdb-add-index/chromium-dev/ELRuj1BDCL4/5Ki4LGx41CcJ
 for more info.
 
 You can improve GDB load time significantly at the cost of link time by
-plitting symbols from the object files. In GN, set `use_debug_fission=false` in
-your "gn args". In GYP add `linux_use_debug_fission=0` to your `GYP_DEFINES`.
+splitting symbols from the object files. In GN, set `use_debug_fission=false` in
+your "gn args".
 
 ## Core files
 
 `ulimit -c unlimited` should cause all Chrome processes (run from that shell) to
 dump cores, with the possible exception of some sandboxed processes.
 
 Some sandboxed subprocesses might not dump cores unless you pass the
 `--allow-sandbox-debugging` flag.
 
 If the problem is a freeze rather than a crash, you may be able to trigger a
@@ skipping 136 matching lines @@
 
 You can use valgrind on chrome and/or on the renderers e.g
 `valgrind --smc-check=all ../sconsbuild/Debug/chrome`
 or by passing valgrind as the argument to `--render-cmd-prefix`.
 
 Beware that there are several valgrind "false positives" e.g. pickle, sqlite and
 some instances in webkit that are ignorable. On systems with prelink and address
 space randomization (e.g. Fedora), you may also see valgrind errors in libstdc++
 on startup and in gnome-breakpad.
 
-Valgrind doesn't seem to play nice with tcmalloc. To disable tcmalloc run GYP
+Valgrind doesn't seem to play nice with tcmalloc. To disable tcmalloc set the GN arg:
 
-    $ cd $CHROMIUM_ROOT/src
-    $ build/gyp_chromium -Duse_allocator=none
+    use_allocator="none"
 
 and rebuild.
 
 ## Profiling
 
 See
 https://sites.google.com/a/chromium.org/dev/developers/profiling-chromium-and-webkit
 and [Linux Profiling](linux_profiling.md).
 
 ## i18n
@@ skipping 93 matching lines @@
 [Running layout tests on Linux](layout_tests_linux.md) page.
 
 If you need to test something with hardware accelerated compositing
 (e.g., compiz), you can use `Xgl` (`sudo apt-get install xserver-xgl`). E.g.:
 
     Xgl :1 -ac -accel glx:pbuffer -accel xv:pbuffer -screen 1024x768
 
 ## Mozilla Tips
 
 https://developer.mozilla.org/en/Debugging_Mozilla_on_Linux_FAQ