Add -pie to chrome on Linux in GN.

chrome/BUILD.gn

Index: chrome/BUILD.gn
diff --git a/chrome/BUILD.gn b/chrome/BUILD.gn
index f25dd9c2b5a27ba68219d75ba05fd14235a6c94a..77a67b16540dd0ada9d85397115c8868fe784b75 100644
--- a/chrome/BUILD.gn
+++ b/chrome/BUILD.gn
@@ -116,11 +116,9 @@ if (!is_android) {
       # Needed for chrome_main.cc initialization of libraries.
       configs += [ "//build/config/linux:pangocairo" ]
 
-      # TODO(GYP) ['profiling==0 and linux_disable_pie==0', {
-      #   'ldflags': [
-      #      '-pie',
-      #   ],
-      #}],
+      # GYP has this in a 'profiling==0 and linux_disable_pie==0' condition.
+      # but GN doesn't have either of these flags.
+      ldflags = [ "-pie" ]
 
       if (use_x11) {
         configs += [