Put the syzygy targets behind a 'syzygy_optimize' flag.

build/common.gypi

Index: build/common.gypi
diff --git a/build/common.gypi b/build/common.gypi
index eb86b3e3f71a3e7c60e1f2c8006c9dafa4776112..1713d652e00a621017415b465c8fa17205bd9e4e 100644
--- a/build/common.gypi
+++ b/build/common.gypi
@@ -521,6 +521,9 @@
       'enable_enhanced_bookmarks%': 0,
       'enable_hangout_services_extension%': 0,
 
+       # Enable the Syzygy optimization step.
+      'syzygy_optimize%': 0,
+
       'conditions': [
         # A flag for POSIX platforms
         ['OS=="win"', {
@@ -950,6 +953,7 @@
     'asan%': '<(asan)',
     'asan_coverage%': '<(asan_coverage)',
     'syzyasan%': '<(syzyasan)',
+    'syzygy_optimize%': '<(syzygy_optimize)',
     'lsan%': '<(lsan)',
     'msan%': '<(msan)',
     'msan_blacklist%': '<(msan_blacklist)',
@@ -1298,6 +1302,13 @@
     'video_hole%': 0,
 
     'conditions': [
+      # Enable the Syzygy optimization step for the official builds.
+      ['OS=="win" and buildtype=="Official" and syzyasan!=1', {
+        'syzygy_optimize%': 1,
+      }, {
+        'syzygy_optimize%': 0,
+      }],
+
       # The version of GCC in use, set later in platforms that use GCC and have
       # not explicitly chosen to build with clang. Currently, this means all
       # platforms except Windows, Mac and iOS.