content: Make record_whole_document available for all platforms.

content/public/common/BUILD.gn

Index: content/public/common/BUILD.gn
diff --git a/content/public/common/BUILD.gn b/content/public/common/BUILD.gn
index 9075452a68dd0ddb74335af5d5599432945769bf..94e9d0447769ce463321d9793f6b67d2d7b58686 100644
--- a/content/public/common/BUILD.gn
+++ b/content/public/common/BUILD.gn
@@ -71,6 +71,14 @@ source_set("static_switches") {
   public_configs = [ ":static_switches_defines" ]
 }
 
+# Set only in GN builds, to allow enabling of WebPreferences used on the Blimp
+# engine.
+config("blimp_web_prefs") {
+  if (enable_blimp_web_prefs) {
+    defines = [ "ENABLE_BLIMP_WEB_PREFS" ]

[Wez, 2016/03/22 00:18:14]

Could we instead have this be enable_record_whole_document or something? Seems
strange to bake any understanding of Blimp in at this level.

[Khushal, 2016/03/22 00:21:38]

I assume we would need to add more web prefs for Blimp going forward, for
instance to disable custom fonts. So might be better to put all such changes for
web prefs behind a single flag.

+  }
+}
+
 source_set("common_sources") {
   visibility = [ "//content/*" ]
 
@@ -98,6 +106,7 @@ source_set("common_sources") {
     "//ui/base",
     "//ui/gfx",
   ]
+  all_dependent_configs = [ ":blimp_web_prefs" ]
 
   if (!enable_plugins) {
     sources -= [