Remove unused build override

build_overrides/build.gni

Index: build_overrides/build.gni
diff --git a/build_overrides/build.gni b/build_overrides/build.gni
index c7cc22b53ff123defbe9720f1c01b9d7e1a4b521..fbf95c97dd434327e79de87e973def0208692b6d 100644
--- a/build_overrides/build.gni
+++ b/build_overrides/build.gni
@@ -6,12 +6,9 @@
 # in the file PATENTS.  All contributing project authors may
 # be found in the AUTHORS file in the root of the source tree.
 
-# See https://bugs.chromium.org/p/webrtc/issues/detail?id=5453.
-# Some WebRTC targets require the 10.7 deployment version of the Mac SDK and a
-# 10.11 min SDK but those targets are only used in non-Chromium builds. We can
-# remove this when Chromium drops 10.6 support and also requires 10.7.
+# Some WebRTC targets require a 10.11 min SDK but those targets are only
+# used in non-Chromium builds.
 mac_sdk_min_build_override = "10.11"
-mac_deployment_target_build_override = "10.9"
 
 # Some non-Chromium builds don't support building java targets.
 enable_java_templates = true