iOS HW H264 support.

talk/build/common.gypi

Index: talk/build/common.gypi
diff --git a/talk/build/common.gypi b/talk/build/common.gypi
index 36a96c5c5585de327b4f80d2382116f19bcc65e1..b828024be325306c8f27f8ddb17512c42954a03d 100644
--- a/talk/build/common.gypi
+++ b/talk/build/common.gypi
@@ -51,6 +51,10 @@
 
     # Disable this to skip building source requiring GTK.
     'use_gtk%': 1,
+
+    # Enable this to use HW H.264 encoder/decoder on iOS/Mac peerconnections.
+    # Enabling this may break interop with Android clients that support H264.
+    'use_objc_h264%': 0,
   },
   'target_defaults': {
     'include_dirs': [
@@ -139,6 +143,11 @@
           'CARBON_DEPRECATED=YES',
         ],
       }],
+      ['OS=="ios" and (use_objc_h264==1)', {
+        'defines': [
+          'WEBRTC_OBJC_H264',
+        ],
+      }],
       ['os_posix==1', {
         'configurations': {
           'Debug_Base': {