build: move libcc patches to electron repo (#14104)

In the GN build, libchromiumcontent is no longer a distinct library, but
merely a container for a set of scripts and patches. Maintaining those
patches in a separate repository is tedious and error-prone, so merge
them into the main repo.

Once this is merged and GN is the default way to build Electron, the
libchromiumcontent repository can be archived.

patches/common/chromium/mas-cfisobjc.patch

@@ -0,0 +1,44 @@
+From 9fb1ac04b1a3e7ec53e27cf1f413469d04360d1e Mon Sep 17 00:00:00 2001
+From: Jeremy Apthorp <jeremya@chromium.org>
+Date: Mon, 6 Aug 2018 17:11:14 -0700
+Subject: fix: [mas] remove usage of _CFIsObjC
+
+---
+ base/mac/foundation_util.mm | 7 +------
+ 1 file changed, 1 insertion(+), 6 deletions(-)
+
+diff --git a/base/mac/foundation_util.mm b/base/mac/foundation_util.mm
+index aec8c0f6398c..6a6dfc272d45 100644
+--- a/base/mac/foundation_util.mm
++++ b/base/mac/foundation_util.mm
+@@ -25,7 +25,6 @@
+ extern "C" {
+ CFTypeID SecACLGetTypeID();
+ CFTypeID SecTrustedApplicationGetTypeID();
+-Boolean _CFIsObjC(CFTypeID typeID, CFTypeRef obj);
+ }  // extern "C"
+ #endif
+ 
+@@ -323,8 +322,7 @@ NSFont* CFToNSCast(CTFontRef cf_val) {
+       const_cast<NSFont*>(reinterpret_cast<const NSFont*>(cf_val));
+   DCHECK(!cf_val ||
+          CTFontGetTypeID() == CFGetTypeID(cf_val) ||
+-         (_CFIsObjC(CTFontGetTypeID(), cf_val) &&
+-          [ns_val isKindOfClass:[NSFont class]]));
++         ([ns_val isKindOfClass:[NSFont class]]));
+   return ns_val;
+ }
+ 
+@@ -392,9 +390,6 @@ CFCast<CTFontRef>(const CFTypeRef& cf_val) {
+     return (CTFontRef)(cf_val);
+   }
+ 
+-  if (!_CFIsObjC(CTFontGetTypeID(), cf_val))
+-    return NULL;
+-
+   id<NSObject> ns_val = reinterpret_cast<id>(const_cast<void*>(cf_val));
+   if ([ns_val isKindOfClass:[NSFont class]]) {
+     return (CTFontRef)(cf_val);
+-- 
+2.17.0
+