Add checkout_google_benchmark GN variable to DEPS.

This variable is required for V8 8.6.51 and newer, even though PDFium
itself does not use this benchmark mechanism as of this writing. Add
this DEPS entry to allow future V8 DEPS rolls to work.

Change-Id: Ibe0c3ed3911f13ecf7197f62b6dd2db3ae995a93
Reviewed-on: https://pdfium-review.googlesource.com/c/pdfium/+/71152
Reviewed-by: Tom Sepez <tsepez@chromium.org>
Commit-Queue: Lei Zhang <thestig@chromium.org>
diff --git a/DEPS b/DEPS
index 883a1ae..73c64c7 100644
--- a/DEPS
+++ b/DEPS
@@ -3,6 +3,7 @@
 
 gclient_gn_args_file = 'pdfium/build/config/gclient_args.gni'
 gclient_gn_args = [
+  'checkout_google_benchmark',
   'mac_xcode_version',
 ]
 
@@ -13,6 +14,11 @@
   # purposes.
   'checkout_configuration': 'default',
 
+  # By default, do not check out Google Benchmark. This only exists to satisfy
+  # V8-enabled builds that require this variable. Running Google Benchmark is
+  # not supported with PDFium.
+  'checkout_google_benchmark': False,
+
   'checkout_instrumented_libraries': 'checkout_linux and checkout_configuration != "small"',
 
   # This can be overridden, e.g. with custom_vars, to download a nonstandard