Revert r144460 "Remove the linux-only CR_SOURCE_ROOT environment variable...

Revert r144460 "Remove the linux-only CR_SOURCE_ROOT environment variable override of base::DIR_SOURCE_ROOT."

CR_SOURCE_ROOT is used in practice by linux user(s), plural still to be
determined, mostly for ChromeOS related development.

R=willchan@chromium.org
BUG=
TEST=


Review URL: https://chromiumcodereview.appspot.com/10808048

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@148621 0039d316-1c4b-4281-b951-d872f2087c98

base/base_paths_posix.cc

@@ -74,6 +74,20 @@ bool PathProviderPosix(int key, FilePath* result) {
 #endif
     }
     case base::DIR_SOURCE_ROOT: {
+      // Allow passing this in the environment, for more flexibility in build
+      // tree configurations (sub-project builds, gyp --output_dir, etc.)
+      scoped_ptr<base::Environment> env(base::Environment::Create());
+      std::string cr_source_root;
+      if (env->GetVar("CR_SOURCE_ROOT", &cr_source_root)) {
+        path = FilePath(cr_source_root);
+        if (file_util::PathExists(path)) {
+          *result = path;
+          return true;
+        } else {
+          DLOG(WARNING) << "CR_SOURCE_ROOT is set, but it appears to not "
+                        << "point to a directory.";
+        }
+      }
       // On POSIX, unit tests execute two levels deep from the source root.
       // For example:  out/{Debug|Release}/net_unittest
       if (PathService::Get(base::DIR_EXE, &path)) {

testing/test_env.py

@@ -25,11 +25,15 @@ def fix_python_path(cmd):
 
 def run_executable(cmd, env):
   """Runs an executable with:
+    - environment variable CR_SOURCE_ROOT set to the root directory.
     - environment variable LANGUAGE to en_US.UTF-8.
     - Reuses sys.executable automatically.
   """
   # Many tests assume a English interface...
   env['LANGUAGE'] = 'en_US.UTF-8'
+  # Used by base/base_paths_linux.cc as an override. Just make sure the default
+  # logic is used.
+  env.pop('CR_SOURCE_ROOT', None)
   # Ensure paths are correctly separated on windows.
   cmd[0] = cmd[0].replace('/', os.path.sep)
   cmd = fix_python_path(cmd)