Fail to build with unbound Info.plist substitutions instead of silently dropping them.

extensions/shell/app/app-Info.plist

Index: extensions/shell/app/app-Info.plist
diff --git a/extensions/shell/app/app-Info.plist b/extensions/shell/app/app-Info.plist
index 269fd96fa36302f19e6d77bfef277044b1e55080..62bc1d1303500c606d7db77aeb4721f4b64a296c 100644
--- a/extensions/shell/app/app-Info.plist
+++ b/extensions/shell/app/app-Info.plist
@@ -25,7 +25,7 @@
 	<key>NSPrincipalClass</key>
 	<string>NSApplication</string>
 	<key>LSMinimumSystemVersion</key>
-	<string>${MACOSX_DEPLOYMENT_TARGET}.0</string>
+	<string>10.9.0</string>

[sdefresne, 2017/06/27 08:26:25]

I don't like hardcoding the value here. It is available in GN via the
"mac_deployment_target" variable from build/config/mac/mac_sdk.gni, can't we
instead add the following to the template that does variable substitution on
.plist files:

  MACOSX_DEPLOYMENT_TARGET=$mac_deployment_target

This will avoid requiring to grep all files for "10.9" when this variable is
updated.

[Sidney San Martín, 2017/06/27 19:45:50]

Done. I just remembered why it was like this in the original CL: at that point,
our minimum supported macOS version was 10.9, but our build deployment target
was 10.7, and I was discouraged from adding a separate build variable that would
just be used in Info.plists. Now the target is back in sync :) (crbug/580152).

 	<key>LSFileQuarantineEnabled</key>
 	<true/>
 	<key>NSSupportsAutomaticGraphicsSwitching</key>