linux: improve support for cross-compiling

build/common.gypi

 # Copyright (c) 2009 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.
 
 {
   'variables': {
     # .gyp files should set chromium_code to 1 if they build Chromium-specific
     # code, as opposed to external code.  This variable is used to control
     # such things as the set of warnings to enable, and whether warnings are
     # treated as errors.
@@ skipping 83 matching lines @@
     # The architecture that we're building on.
     'target_arch%': 'ia32',
 
     # By default linux does not use views. To turn on views in Linux
     # set the variable GYP_DEFINES to "toolkit_views=1", or modify
     # ~/.gyp/include.gypi .
     'toolkit_views%': 0,
 
     'chromeos%': 0,
 
+    # The system root for cross-compiles. Default: none.
+    'sysroot%': '',
+
     # This is the location of the sandbox binary. Chrome looks for this before
     # running the zygote process. If found, and SUID, it will be used to
     # sandbox the zygote process and, thus, all renderer processes.
     'linux_sandbox_path%': '',
 
     'conditions': [
       ['OS=="linux"', {
         'conditions': [
           ['branding=="Chrome" or linux_chromium_breakpad==1', {
             'linux_breakpad%': 1,
@@ skipping 411 matching lines @@
               ['chromeos==1', {
                 'cflags': [
                   '-march=armv7-a',
                   '-mtune=cortex-a8',
                   '-mfpu=vfp',
                   '-mfloat-abi=softfp',
                 ],
               }],
             ],
           }],
+          ['sysroot!=""', {
+            'cflags': [
+              '--sysroot=<(sysroot)',
+            ],
+            'ldflags': [
+              '--sysroot=<(sysroot)',
+            ],
+          }],
           ['no_strict_aliasing==1', {
             'cflags': [
               '-fno-strict-aliasing',
             ],
           }],
           ['linux_breakpad==1', {
             'cflags': [ '-gstabs' ],
             'defines': ['USE_LINUX_BREAKPAD'],
           }],
         ],
@@ skipping 214 matching lines @@
     # xcode_settings sections, or better yet, should use non-Xcode-specific
     # 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',
   },
-}
+}