linux: use an in-tree copy of gold by default

build/common.gypi

 # Copyright (c) 2012 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.
 
 # IMPORTANT:
 # Please don't directly include this file if you are building via gyp_chromium,
 # since gyp_chromium is automatically forcing its inclusion.
 {
   # Variables expected to be overriden on the GYP command line (-D) or by
   # ~/.gyp/include.gypi.
@@ skipping 358 matching lines @@
         # Turn precompiled headers on by default for VS 2010.
         ['OS=="win" and MSVS_VERSION=="2010"', {
           'chromium_win_pch%': 1
         }],
 
         ['use_aura==1 or chromeos==1', {
           'enable_plugin_installation%': 0,
         }, {
           'enable_plugin_installation%': 1,
         }],
+
+        # Set to 0 to not use third_party/gold as the linker.
+        # On by default for x64 Linux.  Off for ChromeOS as cross-compiling
+        # makes things complicated.
+        ['chromeos==0 and host_arch=="x64"', {
+          'linux_use_gold_binary%': 1,
+        }, {
+          'linux_use_gold_binary%': 0,
+        }],
       ],
     },
 
     # Copy conditionally-set variables out one scope.
     'branding%': '<(branding)',
     'buildtype%': '<(buildtype)',
     'target_arch%': '<(target_arch)',
     'host_arch%': '<(host_arch)',
     'library%': 'static_library',
     'toolkit_views%': '<(toolkit_views)',
@@ skipping 38 matching lines @@
     'safe_browsing%': '<(safe_browsing)',
     'input_speech%': '<(input_speech)',
     'notifications%': '<(notifications)',
     'clang_use_chrome_plugins%': '<(clang_use_chrome_plugins)',
     'asan%': '<(asan)',
     'order_text_section%': '<(order_text_section)',
     'enable_register_protocol_handler%': '<(enable_register_protocol_handler)',
     'enable_web_intents%': '<(enable_web_intents)',
     'enable_web_intents_tag%': '<(enable_web_intents_tag)',
     'enable_plugin_installation%': '<(enable_plugin_installation)',
+    'linux_use_gold_binary%': '<(linux_use_gold_binary)',
     'use_canvas_skia_skia%': '<(use_canvas_skia_skia)',
     # Whether to build for Wayland display server
     'use_wayland%': 0,
 
     # Use system yasm instead of bundled one.
     'use_system_yasm%': 0,
 
     # Default to enabled PIE; this is important for ASLR but we need to be
     # able to turn it off for remote debugging on Chromium OS
     'linux_disable_pie%': 0,
@@ skipping 1527 matching lines @@
             'variables': {'linux_use_tcmalloc%': 1},
             'defines': ['USE_HEAPCHECKER'],
           }],
           ['linux_use_tcmalloc==0', {
             'defines': ['NO_TCMALLOC'],
           }],
           ['linux_keep_shadow_stacks==1', {
             'defines': ['KEEP_SHADOW_STACKS'],
             'cflags': ['-finstrument-functions'],
           }],
+          ['linux_use_gold_binary==1', {
+            'variables': {
+              # We pass the path to gold to the compiler.  gyp leaves
+              # unspecified what the cwd is when running the compiler,
+              # so the normal gyp path-munging fails us.  This hack
+              # gets the right path.
+              'gold_path': '<(PRODUCT_DIR)/../../third_party/gold',
+            },
+            'ldflags': [
+              # Put our gold binary in the search path for the linker.
+              '-B<(gold_path)',
+            ],
+          }],
         ],
       },
     }],
     # FreeBSD-specific options; note that most FreeBSD options are set above,
     # with Linux.
     ['OS=="freebsd"', {
       'target_defaults': {
         'ldflags': [
           '-Wl,--no-keep-memory',
         ],
@@ skipping 744 matching lines @@
     # settings in target dicts.  SYMROOT is a special case, because many other
     # Xcode variables depend on it, including variables such as
     # PROJECT_DERIVED_FILE_DIR.  When a source group corresponding to something
     # like PROJECT_DERIVED_FILE_DIR is added to a project, in order for the
     # files to appear (when present) in the UI as actual files and not red
     # red "missing file" proxies, the correct path to PROJECT_DERIVED_FILE_DIR,
     # and therefore SYMROOT, needs to be set at the project level.
     'SYMROOT': '<(DEPTH)/xcodebuild',
   },
 }