Integrate syzygy (optionally) into the chrome build process.

chrome/chrome_exe.gypi

Index: chrome/chrome_exe.gypi
===================================================================
--- chrome/chrome_exe.gypi	(revision 95033)
+++ chrome/chrome_exe.gypi	(working copy)
@@ -415,10 +415,21 @@
           ],
         }],
         ['OS=="mac" or OS=="win"', {
-          'dependencies': [
-            # On Windows and Mac, make sure we've built chrome_dll, which
-            # contains all of the library code with Chromium functionality.
-            'chrome_dll',
+          'conditions': [
+            ['OS=="win" and optimize_with_syzygy==1', {
+              'dependencies': [
+                # When syzygy is enabled on Windows, make sure we've built the
+                # original chrome_dll, so that the optimize step can run. The
+                # optimization step will generate the final chrome_dll.
+                'original_chrome_dll',
+              ],
+            }, {
+              'dependencies': [
+                # On Windows and Mac, make sure we've built chrome_dll, which
+                # contains all of the library code with Chromium functionality.
+                'chrome_dll',
+              ],
+           }],
           ],
         }],
         ['OS=="win"', {