Set default cross compiler for ARM/linux builds.

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 3368 matching lines @@
       # enabled when not building on Chrome OS.
       # TODO(phajdan.jr): Use -fstack-protector-strong when our gcc
       # supports it.
       'target_defaults': {
         'cflags': [
           '-fstack-protector',
           '--param=ssp-buffer-size=4',
         ],
       },
     }],
+    ['OS=="linux" and target_arch=="arm" and host_arch!="arm" and chromeos==0 and clang==0', {
+      # Some sensible defaults for ARM cross compiling on linux.  These can be overridden

[Mark Seaborn, 2014/07/28 15:55:20]

Line is >80 chars

[Sam Clegg, 2014/07/29 00:28:11]

There are other occurrences of conditions in this file that overflow the 80 char
line so I assumed that was ok (line 110, line 211 for example).

+      # using CC/CXX/etc environment variables.
+      'make_global_settings': [
+        ['CC', '<!(which arm-linux-gnueabihf-gcc)'],

[Mark Seaborn, 2014/07/28 15:55:20]

The bot configs also set AR, AS and RANLIB (see
https://src.chromium.org/viewvc/chrome/trunk/tools/build/scripts/slave/recipe...).
 Are any of those necessary?

[Sam Clegg, 2014/07/29 00:28:11]

Apparently not.  Its hard to be 100% since there are C++11 issues that currently
make building with arm/gcc on precise impossible, but I can build many targets.

+        ['CXX', '<!(which arm-linux-gnueabihf-g++)'],
+        ['CC.host', '<!(which gcc)'],
+        ['CXX.host', '<!(which g++)'],
+      ],
+    }],
     ['os_posix==1 and OS!="mac" and OS!="ios"', {
       'target_defaults': {
         # Enable -Werror by default, but put it in a variable so it can
         # be disabled in ~/.gyp/include.gypi on the valgrind builders.
         'variables': {
           'werror%': '-Werror',
           'libraries_for_target%': '',
         },
         'defines': [
           '_FILE_OFFSET_BITS=64',
@@ skipping 2171 matching lines @@
       # it won't depend on the environment at make time.
       'make_global_settings': [
         ['CC', '<!(/bin/echo -n <(android_toolchain)/*-gcc)'],
         ['CXX', '<!(/bin/echo -n <(android_toolchain)/*-g++)'],
         ['CC.host', '<!(which gcc)'],
         ['CXX.host', '<!(which g++)'],
       ],
     }],
     ['OS=="linux" and target_arch=="mipsel"', {
       'make_global_settings': [
         ['CC', '<(sysroot)/../bin/mipsel-linux-gnu-gcc'],

[Mark Seaborn, 2014/07/28 15:55:20]

Should your code go after these blocks, which are similar?

[Nico, 2014/07/28 16:01:40]

+1, if that works that'd be better.

[Sam Clegg, 2014/07/29 00:28:11]

Done.

[Sam Clegg, 2014/07/29 00:28:11]

Done.

         ['CXX', '<(sysroot)/../bin/mipsel-linux-gnu-g++'],
         ['CC.host', '<!(which gcc)'],
         ['CXX.host', '<!(which g++)'],
       ],
     }],
 
     # TODO(yyanagisawa): supports GENERATOR==make
     #  make generator doesn't support CC_wrapper without CC
     #  in make_global_settings yet.
     ['use_goma==1 and ("<(GENERATOR)"=="ninja" or clang==1)', {
@@ skipping 67 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',
   },
 }