Hack to make tests work if out is a symlink: see if the current dir is the source root.

base/base_paths_linux.cc

 // Copyright (c) 2006-2008 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.
 
 #include "base/base_paths_linux.h"
 
 #include <unistd.h>
 
 #include "base/file_path.h"
 #include "base/file_util.h"
@@ skipping 21 matching lines @@
         NOTREACHED() << "Unable to resolve " << kSelfExe << ".";
         return false;
       }
       bin_dir[bin_dir_size] = 0;
       *result = FilePath(bin_dir);
       return true;
     }
     case base::DIR_SOURCE_ROOT:
       // On linux, unit tests execute two levels deep from the source root.
       // For example:  sconsbuild/{Debug|Release}/net_unittest
-      if (!PathService::Get(base::DIR_EXE, &path))
-        return false;
-      path = path.Append(FilePath::kParentDirectory)
-                 .Append(FilePath::kParentDirectory);
-      *result = path;
-      return true;
+      if (PathService::Get(base::DIR_EXE, &path)) {
+        path = path.DirName().DirName();
+        if (file_util::PathExists(path.Append("base/base_paths_linux.cc"))) {
+          *result = path;
+          return true;
+        }
+      }
+      // If that failed (maybe the build output is symlinked to a different
+      // drive) try assuming the current directory is the source root.
+      if (file_util::GetCurrentDirectory(&path) &&
+          file_util::PathExists(path.Append("base/base_paths_linux.cc"))) {
+        *result = path;
+        return true;
+      }
+      LOG(ERROR) << "Couldn't find your source root.  "
+                 << "Try running from your chromium/src directory.";
+      return false;
   }
   return false;
 }
 
 }  // namespace base