Add cross-platform API to get the form factor of the device

chrome/common/form_factor_ios.mm

Index: chrome/common/form_factor_ios.mm
diff --git a/chrome/common/form_factor_ios.mm b/chrome/common/form_factor_ios.mm
new file mode 100644
index 0000000000000000000000000000000000000000..15f72ca22e48ec19c27fc19dd11a1a5c050c9779
--- /dev/null
+++ b/chrome/common/form_factor_ios.mm
@@ -0,0 +1,11 @@
+// Copyright
+
+#include "form_factor.h"
+
+Study_FormFactor GetFormFactor() {
+  UIUserInterfaceIdiom idiom = [[UIDevice currentDevice] userInterfaceIdiom];

[Alexei Svitkine (slow), 2013/10/29 15:26:21]

This probably needs some include. You can probably google the UIDevice API and
see what header it comes from. Use try jobs to see if it compiles.

[yao, 2013/10/29 19:21:57]

Done.

+  if (idiom == UIUserInterfaceIdiomPad) {
+    return Study_FormFactor_TABLET;
+  }
+  return Study_FormFactor_PHONE;
+}