Fallback to '.tbd' for system missing '.dylib'.

pylib/gyp/xcode_emulation.py

Index: pylib/gyp/xcode_emulation.py
diff --git a/pylib/gyp/xcode_emulation.py b/pylib/gyp/xcode_emulation.py
index 47f9d520e10e0206be9cc7d32df2eedc61db57ea..5de9ac121d61f97351942ea8880f4dfdcd6cbbd6 100644
--- a/pylib/gyp/xcode_emulation.py
+++ b/pylib/gyp/xcode_emulation.py
@@ -1032,7 +1032,23 @@ class XcodeSettings(object):
     sdk_root = self._SdkPath(config_name)
     if not sdk_root:
       sdk_root = ''
-    return l.replace('$(SDKROOT)', sdk_root)
+    # Xcode 7 started shipping with ".tbd" (text based stubs) files instead of
+    # ".dylib" without providing a real support for them. What it does, for
+    # "/usr/lib" libraries, is do "-L/usr/lib -lname" which is dependent on the
+    # library order and cause collision when building Chrome.
+    #
+    # Instead substitude ".tbd" to ".dylib" in the generated project when the
+    # following conditions are both true:
+    # - library is referenced in the gyp file as "$(SDKROOT)/**/*.dylib",
+    # - the ".dylib" file does not exists but a ".tbd" file do.
+    library = l.replace('$(SDKROOT)', sdk_root)
+    if l.startswith('$(SDKROOT)'):
+      basename, ext = os.path.splitext(library)
+      if ext == '.dylib' and not os.path.exists(library):
+        tbd_library = basename + '.tbd'
+        if os.path.exists(tbd_library):
+          library = tbd_library
+    return library
 
   def AdjustLibraries(self, libraries, config_name=None):
     """Transforms entries like 'Cocoa.framework' in libraries into entries like