Add public deps to GN

tools/gn/group_target_generator.cc

Index: tools/gn/group_target_generator.cc
diff --git a/tools/gn/group_target_generator.cc b/tools/gn/group_target_generator.cc
index b2a73d6684e769a086aaee908c6095b7890660c8..64fa92096f67cfb22eb111639b7067151795a0b1 100644
--- a/tools/gn/group_target_generator.cc
+++ b/tools/gn/group_target_generator.cc
@@ -4,6 +4,8 @@
 
 #include "tools/gn/group_target_generator.h"
 
+#include "tools/gn/variables.h"
+
 GroupTargetGenerator::GroupTargetGenerator(
     Target* target,
     Scope* scope,
@@ -19,4 +21,13 @@ void GroupTargetGenerator::DoRun() {
   target_->set_output_type(Target::GROUP);
   // Groups only have the default types filled in by the target generator
   // base class.
+
+  // Before there was a deps/public_deps split, a group acted like all deps
+  // are public. During a transition period, if public_deps is not defined,
+  // treat all deps as public. This should be removed and existing groups
+  // updated to use "public_deps" when needed.
+  if (scope_->GetValue(variables::kDeps, false) &&
+      !scope_->GetValue(variables::kPublicDeps, false)) {
+    std::swap(target_->private_deps(), target_->public_deps());
+  }
 }