[GN] Add JSON project writer

tools/gn/visibility.cc

Index: tools/gn/visibility.cc
diff --git a/tools/gn/visibility.cc b/tools/gn/visibility.cc
index a61a5cd9c45f7effb57fd053be21ddaf29a6122e..0c4eecc9339fbe10df200b436e89d558aa03c3d2 100644
--- a/tools/gn/visibility.cc
+++ b/tools/gn/visibility.cc
@@ -4,8 +4,10 @@
 
 #include "tools/gn/visibility.h"
 
+#include "base/memory/ptr_util.h"
 #include "base/strings/string_piece.h"
 #include "base/strings/string_util.h"
+#include "base/values.h"
 #include "tools/gn/err.h"
 #include "tools/gn/filesystem_utils.h"
 #include "tools/gn/item.h"
@@ -83,6 +85,14 @@ std::string Visibility::Describe(int indent, bool include_brackets) const {
   return result;
 }
 
+std::unique_ptr<base::Value> Visibility::AsValue() const {
+  auto* res = new base::ListValue();
+  for (const auto& pattern : patterns_) {

[brettw, 2016/07/06 22:19:27]

The style guide says we can do it either way but to be consistent, and I've been
trying to be consistent in GN to not use {} for these single-line conditionals
and loops (we'd always use {} for multi-line ones, even if it's still only one
statement). Can you delete the {} from here and in other places where you have
added them?

[matt.k, 2016/07/08 00:39:08]

Done.

+    res->AppendString(pattern.Describe());
+  }
+  return WrapUnique(res);
+}
+
 // static
 bool Visibility::CheckItemVisibility(const Item* from,
                                      const Item* to,
@@ -93,7 +103,7 @@ bool Visibility::CheckItemVisibility(const Item* from,
         "The item " + from->label().GetUserVisibleName(false) + "\n"
         "can not depend on " + to_label + "\n"
         "because it is not in " + to_label + "'s visibility list: " +
-        to->visibility().Describe(0, true));
+                   to->visibility().Describe(0, true));
     return false;
   }
   return true;