Add a new FORCE_DETERMINISTIC_BUILD define.

This flag will be used to make the builds determinist, e.g. in place like this one: https://code.google.com/p/chromium/codesearch#chromium/src/base/build_time.h&l=15

BUG=314403

Review URL: https://codereview.chromium.org/324403006

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@276801 0039d316-1c4b-4281-b951-d872f2087c98

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

build/config/BUILD.gn

@@ -12,6 +12,12 @@ declare_args() {
   # that is normally turned on for Debug builds. These are generally useful for
   # catching bugs but in some cases may cause conflicts or excessive slowness.
   disable_iterator_debugging = false
+
+  # Set to true 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 = false
 }
 
 # TODO(brettw) Most of these should be removed. Instead of global feature
@@ -71,6 +77,9 @@ config("feature_flags") {
   if (enable_spellcheck) {
     defines += [ "ENABLE_SPELLCHECK=1" ]
   }
+  if (force_deterministic_build) {
+    defines += [ "FORCE_DETERMINISTIC_BUILD" ]
+  }
   if (use_udev) {
     # TODO(brettw) should probably be "=1".
     defines += [ "USE_UDEV" ]