Support explicit pools in actions

tools/gn/function_toolchain.cc

Index: tools/gn/function_toolchain.cc
diff --git a/tools/gn/function_toolchain.cc b/tools/gn/function_toolchain.cc
index 05c764bfbdf65ab5524c8c15ae48221b7a2d63dc..6850668bc932c05b8bf1084611209943f1855c86 100644
--- a/tools/gn/function_toolchain.cc
+++ b/tools/gn/function_toolchain.cc
@@ -1051,12 +1051,12 @@ Value RunTool(Scope* scope,
     return Value();
   }
 
-  if (tool_type != Toolchain::TYPE_COPY &&
-      tool_type != Toolchain::TYPE_STAMP &&
+  if (tool_type != Toolchain::TYPE_COPY && tool_type != Toolchain::TYPE_STAMP &&
       tool_type != Toolchain::TYPE_COPY_BUNDLE_DATA &&
-      tool_type != Toolchain::TYPE_COMPILE_XCASSETS) {
+      tool_type != Toolchain::TYPE_COMPILE_XCASSETS &&
+      tool_type != Toolchain::TYPE_ACTION) {
     // All tools should have outputs, except the copy, stamp, copy_bundle_data
-    // and compile_xcassets tools that generate their outputs internally.
+    // compile_xcassets and action tools that generate their outputs internally.
     if (!ReadPatternList(&block_scope, "outputs", subst_output_validator,
                          tool.get(), &Tool::set_outputs, err) ||
         !ValidateOutputs(tool.get(), err))