Add a new FORCE_DETERMINISTIC_BUILD define.

build/common.gypi

Index: build/common.gypi
diff --git a/build/common.gypi b/build/common.gypi
index 0c1d4152a92ca5ee6835890d98df0baf7a3b4bc3..ca5d0f763b01784d0d2b80bc31cb396df9a47e83 100644
--- a/build/common.gypi
+++ b/build/common.gypi
@@ -271,6 +271,12 @@
       # on compile-only bots).
       'fastbuild%': 0,
 
+      # Set to 1 to force deterministic builds (this isn't working yet but this
+      # flag will help us to get there). See http://crbug.com/314403.
+      # TODO(sebmarchand): Update this comment once this flag guarantee a
+      #     deterministic build.
+      'force_deterministic_build%': 0,
+
       # Set to 1 to force Visual C++ to use legacy debug information format /Z7.
       # This is useful for parallel compilation tools which can't support /Zi.
       # Only used on Windows.
@@ -292,7 +298,6 @@
       # Detect NEON support at run-time.
       'arm_neon_optional%': 0,
 
-
       # Use libjpeg-turbo as the JPEG codec used by Chromium.
       'use_libjpeg_turbo%': 1,
 
@@ -1021,6 +1026,7 @@
     'use_xi2_mt%':'<(use_xi2_mt)',
     'image_loader_extension%': '<(image_loader_extension)',
     'fastbuild%': '<(fastbuild)',
+    'force_deterministic_build%': '<(force_deterministic_build)',
     'win_z7%': '<(win_z7)',
     'dcheck_always_on%': '<(dcheck_always_on)',
     'tracing_like_official_build%': '<(tracing_like_official_build)',
@@ -2570,6 +2576,11 @@
           }], # clang!=1
         ],
       }],  # fastbuild!=0
+      ['force_deterministic_build==1', {
+        'defines': [
+          'FORCE_DETERMINISTIC_BUILD',
+        ],
+      }],  # force_deterministic_build==1
       ['dcheck_always_on!=0', {
         'defines': ['DCHECK_ALWAYS_ON=1'],
       }],  # dcheck_always_on!=0