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 c79e8e76ee7ce79ea4b8f3becf125a1544c84c49..7f061ceb415531b9146fc874a5bdf66ebc8d5d3c 100644
--- a/build/common.gypi
+++ b/build/common.gypi
@@ -518,6 +518,9 @@
       '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"', {
@@ -826,6 +829,13 @@
         }, {
           'icu_use_data_file_flag%' : 0,
         }],
+
+        # Enable the Syzygy optimization step for the official builds.
+        ['OS=="win" and buildtype=="Official"', {
+          'syzygy_optimize%': 1,
+        }, {
+          'syzygy_optimize%': 0,
+        }],

[chrisha, 2014/03/14 22:01:36]

Is there any meaningful way for us to explode with a message if both
syzygy_optimize and syzyasan are set?

[Sébastien Marchand, 2014/03/17 17:41:14]

No (afaik), I've added an extra check here but preventing both variables to be
set seems tricky...(i.e. we'll have to run a command that will fail and print
the message)

       ],
 
       # Set this to 1 to enable use of concatenated impulse responses
@@ -939,6 +949,7 @@
     'asan%': '<(asan)',
     'asan_coverage%': '<(asan_coverage)',
     'syzyasan%': '<(syzyasan)',
+    'syzygy_optimize%': '<(syzygy_optimize)',
     'lsan%': '<(lsan)',
     'msan%': '<(msan)',
     'msan_blacklist%': '<(msan_blacklist)',