mac: Turn on partial availability warning.

build/common.gypi

Index: build/common.gypi
diff --git a/build/common.gypi b/build/common.gypi
index 2f5ea2d1ca409171500de7853b635c68a234b13a..0410775b13216f5918f1c205684257fc234c70a5 100644
--- a/build/common.gypi
+++ b/build/common.gypi
@@ -2578,6 +2578,11 @@
       '<(SHARED_INTERMEDIATE_DIR)',
     ],
     'conditions': [
+      ['OS=="mac"', {
+        # When compiling Objective C, warns if a method is used whose
+        # availability is newer than the deployment target.
+        'variables': { 'clang_warning_flags': ['-Wpartial-availability']},

[Nico, 2015/05/19 01:40:31]

If this is only for mac anyways, you could instead also do

  xcode_settings: { WARNING_CFLAGS: [-Wpartial-availability]}

which is what clang_warning_flags gets translated to here. (The point of
clang_warning_flags is that it sets the flag correctly for mac windows linux
android)

[erikchen, 2015/05/19 17:06:20]

Done.

+      }],
       ['(OS=="mac" or OS=="ios") and asan==1', {
         'dependencies': [
           '<(DEPTH)/build/mac/asan.gyp:asan_dynamic_runtime',