Use --icf=all for Linux64 too.

build/config/compiler/BUILD.gn

 # Copyright (c) 2013 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 import("//build/config/android/config.gni")
 import("//build/config/chrome_build.gni")
 if (current_cpu == "arm") {
   import("//build/config/arm.gni")
 }
 if (current_cpu == "mipsel" || current_cpu == "mips64el") {
@@ skipping 449 matching lines @@
       # Only apply this to the target linker, since the host
       # linker might not be gold, but isn't used much anyway.
       # TODO(raymes): Disable threading because gold is frequently
       # crashing on the bots: crbug.com/161942.
       #"-Wl,--threads",
       #"-Wl,--thread-count=4",
     ]
 
     if (!is_asan && !is_msan && !is_lsan && !is_tsan) {
       # TODO(brettw) common.gypi has this only for target toolset.
-      if (current_cpu == "x64") {
-        # --icf=safe disables much more folding on x86_64 than elsewhere, see
-        # http://crbug.com/492177.  Turning it on saves over 12 MB of binary
-        # size, but it seems to regress cold startup time by over a second
-        # (see http://crbug.com/492809).
-        # TODO(thakis): Check if disabling ICF would inmprove android cold start
-        # times by several seconds too.
-        ldflags += [ "-Wl,--icf=safe" ]
-      } else {
-        ldflags += [ "-Wl,--icf=all" ]
-      }
+      ldflags += [ "-Wl,--icf=all" ]
     }
 
     # TODO(thestig): Make this flag work with GN.
     #if (!is_official_build && !is_chromeos && !(is_asan || is_lsan || is_tsan || is_msan)) {
     #  ldflags += [
     #    "-Wl,--detect-odr-violations",
     #  ]
     #}
   }
 
@@ skipping 766 matching lines @@
       cflags += [ "-gsplit-dwarf" ]
     }
   }
 }
 
 config("no_symbols") {
   if (!is_win) {
     cflags = [ "-g0" ]
   }
 }