docs: Change "ChromeOS" to "Chrome OS".

Correct a common typo/meme in the hopes of reducing its
spread.

BUG=none
TBR=brettw@chromium.org

Review-Url: https://codereview.chromium.org/2697323005
Cr-Original-Commit-Position: refs/heads/master@{#452121}
Cr-Mirrored-From: https://chromium.googlesource.com/chromium/src
Cr-Mirrored-Commit: 8171050893e6d8b3dd2814e89422e09eba952e4b
diff --git a/tools/gn/docs/cross_compiles.md b/tools/gn/docs/cross_compiles.md
index 2d7e8a3..52f9559 100644
--- a/tools/gn/docs/cross_compiles.md
+++ b/tools/gn/docs/cross_compiles.md
@@ -49,7 +49,7 @@
 (We don't have to specify target\_cpu because of the conditionals
 mentioned above).
 
-And, to do a 64-bit MIPS ChromeOS cross-compile:
+And, to do a 64-bit MIPS Chrome OS cross-compile:
 
 ```
 gn gen out/Default --args='target_os="chromeos" target_cpu="mips64el"'
diff --git a/tools/gn/docs/reference.md b/tools/gn/docs/reference.md
index 7e85b10..48a6683 100644
--- a/tools/gn/docs/reference.md
+++ b/tools/gn/docs/reference.md
@@ -3893,7 +3893,7 @@
 
   This should be set to the most specific value possible. So, "android" or
   "chromeos" should be used instead of "linux" where applicable, even though
-  Android and ChromeOS are both Linux variants. This can mean that one needs to
+  Android and Chrome OS are both Linux variants. This can mean that one needs to
   write
 
       if (target_os == "android" || target_os == "linux") {