GN docs: update the example of declare_args().

BUG=None

Review-Url: https://codereview.chromium.org/2714643005
Cr-Original-Commit-Position: refs/heads/master@{#452640}
Cr-Mirrored-From: https://chromium.googlesource.com/chromium/src
Cr-Mirrored-Commit: b7fb5fc4195bd36c81225691ae236363c1d05873
diff --git a/tools/gn/docs/reference.md b/tools/gn/docs/reference.md
index 48a6683..97a2c86 100644
--- a/tools/gn/docs/reference.md
+++ b/tools/gn/docs/reference.md
@@ -1682,7 +1682,7 @@
   }
 
   If you want to override the (default disabled) Doom Melon:
-    gn --args="enable_doom_melon=true enable_teleporter=false"
+    gn --args="enable_doom_melon=true enable_teleporter=true"
   This also sets the teleporter, but it's already defaulted to on so it will
   have no effect.
 
diff --git a/tools/gn/functions.cc b/tools/gn/functions.cc
index 41be19b..272cd94 100644
--- a/tools/gn/functions.cc
+++ b/tools/gn/functions.cc
@@ -429,7 +429,7 @@
   }
 
   If you want to override the (default disabled) Doom Melon:
-    gn --args="enable_doom_melon=true enable_teleporter=false"
+    gn --args="enable_doom_melon=true enable_teleporter=true"
   This also sets the teleporter, but it's already defaulted to on so it will
   have no effect.
 )";