Rename source_root to atom_source_root to avoid conflicts.

atom.gyp

@@ -147,10 +147,11 @@
       '@rpath/Quincy.framework/Versions/A/Quincy',
       '${BUILT_PRODUCTS_DIR}/${EXECUTABLE_PATH}'
     ],
+    'atom_source_root': '<!(python tools/atom_source_root.py)',
   },
   'target_defaults': {
     'mac_framework_dirs': [
-      '<(source_root)/frameworks',
+      '<(atom_source_root)/frameworks',
     ],
   },
   'targets': [

common.gypi

@@ -1,7 +1,6 @@
 {
   'variables': {
     'clang': 0,
-    'source_root': '<!(python tools/mac/source_root.py)',
     'conditions': [
       ['OS=="mac"', {
         'clang': 1,

tools/atom_source_root.py

@@ -6,5 +6,4 @@ import os
 """
 
 
-relative_source_root = os.path.join(__file__, '..', '..', '..')
-print os.path.abspath(relative_source_root)
+print os.path.abspath(os.path.dirname(os.path.dirname(__file__)))