Make some small tweaks to the build instructions.

docs/linux_build_instructions.md

 # Checking out and building Chromium on Linux
 
 **See also [the old version of this page](old_linux_build_instructions.md).**
 
 Google employee? See [go/building-chrome](https://goto.google.com/building-chrome) instead.
 
 [TOC]
 
 ## System requirements
 
 *   A 64-bit Intel machine with at least 8GB of RAM. More than 16GB is highly
     recommended.
 *   At least 100GB of free disk space.
 *   You must have Git and Python installed already.
 
-Most development is done on Ubuntu (currently 14.04, Trusty Tahr).  There are
+Most development is done on Ubuntu (currently 14.04, Trusty Tahr). There are
 some instructions for other distros below, but they are mostly unsupported.
 
 ## Install `depot_tools`
 
-Clone the depot_tools repository:
+Clone the `depot_tools` repository:
 
-    $ git clone https://chromium.googlesource.com/chromium/tools/depot_tools.git
+```shell
+$ git clone https://chromium.googlesource.com/chromium/tools/depot_tools.git
+```
 
-Add depot_tools to the end of your PATH (you will probably want to put this
-in your ~/.bashrc or ~/.zshrc). Assuming you cloned depot_tools
-to /path/to/depot_tools:
+Add `depot_tools` to the end of your PATH (you will probably want to put this
+in your `~/.bashrc` or `~/.zshrc`). Assuming you cloned `depot_tools` to
+`/path/to/depot_tools`:
 
-    $ export PATH=$PATH:/path/to/depot_tools
+```shell
+$ export PATH="$PATH:/path/to/depot_tools"
+```
 
 ## Get the code
 
-Create a chromium directory for the checkout and change to it (you can call
-this whatever you like and put it wherever you like, as
-long as the full path has no spaces):
-    
-    $ mkdir chromium
-    $ cd chromium
+Create a `chromium` directory for the checkout and change to it (you can call
+this whatever you like and put it wherever you like, as long as the full path
+has no spaces):
+
+```shell
+$ mkdir ~/chromium && cd ~/chromium
+```
 
 Run the `fetch` tool from depot_tools to check out the code and its
 dependencies.
 
-    $ fetch --nohooks chromium
+```shell
+$ fetch --nohooks chromium
+```
 
 If you don't want the full repo history, you can save a lot of time by
-adding the `--no-history` flag to fetch.
+adding the `--no-history` flag to `fetch`.
 
 Expect the command to take 30 minutes on even a fast connection, and many
 hours on slower ones.
 
 If you've already installed the build dependencies on the machine (from another
-checkout, for example), you can omit the `--nohooks` flag and fetch
+checkout, for example), you can omit the `--nohooks` flag and `fetch`
 will automatically execute `gclient runhooks` at the end.
 
-When fetch completes, it will have created a directory called `src`.
-The remaining instructions assume you are now in that directory:
+When `fetch` completes, it will have created a hidden `.gclient` file and a
+directory called `src` in the working directory. The remaining instructions
+assume you have switched to the `src` directory:
 
-    $ cd src
+```shell
+$ cd src
+```
 
 ### Install additional build dependencies
 
 Once you have checked out the code, and assuming you're using Ubuntu, run
 [build/install-build-deps.sh](/build/install-build-deps.sh)
 
 Here are some instructions for what to do instead for
 
 * [Debian](linux_debian_build_instructions.md)
 * [Fedora](linux_fedora_build_instructions.md)
 * [Arch Linux](linux_arch_build_instructions.md)
 * [Open SUSE](linux_open_suse_build_instrctions.md)
 * [Mandriva](linux_mandriva_build_instrctions.md)
 
 For Gentoo, you can just run `emerge www-client/chromium`.
 
 ### Run the hooks
 
 Once you've run `install-build-deps` at least once, you can now run the
-chromium-specific hooks, which will download additional binaries and other
+Chromium-specific hooks, which will download additional binaries and other
 things you might need:
 
-    $ gclient runhooks
+```shell
+$ gclient runhooks
+```
 
-*Optional*: You can also [install API keys](https://www.chromium.org/developers/how-tos/api-keys)
-if you want to talk to some of the Google services, but this is not necessary
-for most development and testing purposes.
+*Optional*: You can also [install API
+keys](https://www.chromium.org/developers/how-tos/api-keys) if you want your
+build to talk to some Google services, but this is not necessary for most
+development and testing purposes.
 
-## Seting up the Build
+## Setting up the Build
 
-Chromium uses [Ninja](https://ninja-build.org) as its main build tool, and
-a tool called [GN](../tools/gn/docs/quick_start.md) to generate
-the .ninja files to do the build. To create a build directory, run:
+Chromium uses [Ninja](https://ninja-build.org) as its main build tool along
+with a tool called [GN](../tools/gn/docs/quick_start.md) to generate `.ninja`
+files. You can create any number of *build directories* with different
+configurations. To create a build directory, run:
 
-    $ gn gen out/Default
+```shell
+$ gn gen out/Default
+```
 
-* You only have to do run this command once, it will self-update the build
-  files as needed after that.
-* You can replace `out/Default` with another directory name, but we recommend
-  it should still be a subdirectory of `out`.
-* To specify build parameters for GN builds, including release settings,
-  see [GN build configuration](https://www.chromium.org/developers/gn-build-configuration). 
+* You only have to run this once for each new build directory, Ninja will
+  update the build files as needed.
+* You can replace `Default` with another name, but
+  it should be a subdirectory of `out`.
+* For other build arguments, including release settings, see [GN build
+  configuration](https://www.chromium.org/developers/gn-build-configuration).
   The default will be a debug component build matching the current host
   operating system and CPU.
 * For more info on GN, run `gn help` on the command line or read the
   [quick start guide](../tools/gn/docs/quick_start.md).
 
 ### Faster builds
 
 See [faster builds on Linux](linux_faster_builds.md) for various tips and
 settings that may speed up your build.
 
 ## Build Chromium
 
 Build Chromium (the "chrome" target) with Ninja using the command:
 
-    $ ninja -C out/Default chrome
+```shell
+$ ninja -C out/Default chrome
+```
 
-You can get a list of all of the other build targets from GN by running
-`gn ls out/Default` from the command line. To compile one, pass to Ninja
-the GN label with no preceding "//" (so for `//chrome/test:unit_tests`
-use ninja -C out/Default chrome/test:unit_tests`).
+You can get a list of all of the other build targets from GN by running `gn ls
+out/Default` from the command line. To compile one, pass the GN label to Ninja
+with no preceding "//" (so, for `//chrome/test:unit_tests` use `ninja -C
+out/Default chrome/test:unit_tests`).
 
 ## Run Chromium
 
 Once it is built, you can simply run the browser:
 
-    $ out/Default/chrome
+```shell
+$ out/Default/chrome
+```
 
 ## Running test targets
 
 You can run the tests in the same way. You can also limit which tests are
 run using the `--gtest_filter` arg, e.g.:
 
-    $ ninja -C out/Default unit_tests --gtest_filter="PushClientTest.*"
+```shell
+$ ninja -C out/Default unit_tests --gtest_filter="PushClientTest.*"
+```
 
 You can find out more about GoogleTest at its
 [GitHub page](https://github.com/google/googletest).
 
 ## Update your checkout
 
 To update an existing checkout, you can run
 
-    $ git rebase-update
-    $ gclient sync
+```shell
+$ git rebase-update
+$ gclient sync
+```
 
 The first command updates the primary Chromium source repository and rebases
-any of your local branches on top of tip-of-tree (aka the Git branch `origin/master`).
-If you don't want to use this script, you can also just use `git pull` or 
-other common Git commands to update the repo.
+any of your local branches on top of tip-of-tree (aka the Git branch
+`origin/master`). If you don't want to use this script, you can also just use
+`git pull` or other common Git commands to update the repo.
 
-The second command syncs the subrepositories to the appropriate versions and
-re-runs the hooks as needed.
+The second command syncs dependencies to the appropriate versions and re-runs
+hooks as needed.
 
 ## Tips, tricks, and troubleshooting
 
 ### Linker Crashes
 
 If, during the final link stage:
 
-    LINK out/Debug/chrome
+```
+LINK out/Debug/chrome
+```
 
 You get an error like:
 
-    collect2: ld terminated with signal 6 Aborted terminate called after throwing an
-    instance of 'std::bad_alloc'
-
-    collect2: ld terminated with signal 11 [Segmentation fault], core dumped
+```
+collect2: ld terminated with signal 6 Aborted terminate called after throwing an instance of 'std::bad_alloc'
+collect2: ld terminated with signal 11 [Segmentation fault], core dumped
+```
 
 you are probably running out of memory when linking. You *must* use a 64-bit
 system to build. Try the following build settings (see [GN build
 configuration](https://www.chromium.org/developers/gn-build-configuration) for
-setting):
+other settings):
 
-*   Build in release mode (debugging symbols require more memory).
+*   Build in release mode (debugging symbols require more memory):
     `is_debug = false`
-*   Turn off symbols. `symbol_level = 0`
-*   Build in component mode (this is for developers only, it will be slower and
-    may have broken functionality). `is_component_build = true`
+*   Turn off symbols: `symbol_level = 0`
+*   Build in component mode (this is for development only, it will be slower and
+    may have broken functionality): `is_component_build = true`
 
 ### More links
 
 *   Information about [building with Clang](clang.md).
 *   You may want to [use a chroot](using_a_linux_chroot.md) to
     isolate yourself from versioning or packaging conflicts.
 *   Cross-compiling for ARM? See [LinuxChromiumArm](linux_chromium_arm.md).
 *   Want to use Eclipse as your IDE? See
     [LinuxEclipseDev](linux_eclipse_dev.md).
 *   Want to use your built version as your 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.