[GN] Add support for generating Xcode projects.

tools/gn/create_bundle_target_generator.cc

Index: tools/gn/create_bundle_target_generator.cc
diff --git a/tools/gn/create_bundle_target_generator.cc b/tools/gn/create_bundle_target_generator.cc
index 608541911e1248a6173d9c16a886140d59771230..83749983e6d00383666f6f7628287ecbbb5a9926 100644
--- a/tools/gn/create_bundle_target_generator.cc
+++ b/tools/gn/create_bundle_target_generator.cc
@@ -41,6 +41,14 @@ void CreateBundleTargetGenerator::DoRun() {
                     variables::kBundlePlugInsDir,
                     &bundle_data.plugins_dir()))
     return;
+
+  const Value* value = scope_->GetValue(variables::kProductType, true);
+  if (value) {
+    if (!value->VerifyTypeIs(Value::STRING, err_))
+      return;
+
+    bundle_data.product_type().assign(value->string_value());
+  }
 }
 
 bool CreateBundleTargetGenerator::GetBundleDir(
@@ -53,6 +61,8 @@ bool CreateBundleTargetGenerator::GetBundleDir(
   if (!value->VerifyTypeIs(Value::STRING, err_))
     return false;
   std::string str = value->string_value();
+  if (!str.empty() && str[str.size() - 1] != '/')

[sdefresne, 2016/04/27 17:41:53]

Without this "bundle_dir->SwapValue(&str);" causes a DCHECK because the BUILD.gn
files do not use trailing "/". Is it better to fix the BUILD.gn files or to fix
the code here? The DCHECK is pre-existing my CL (it was introduced by recent
change by rsesek).

+    str.push_back('/');
   if (!EnsureStringIsInOutputDir(GetBuildSettings()->build_dir(), str,
                                  value->origin(), err_))
     return false;