Add ninja console pool support to GN

tools/gn/variables.cc

Index: tools/gn/variables.cc
diff --git a/tools/gn/variables.cc b/tools/gn/variables.cc
index e7782d73bd7c81293cdc76574f3018b44d0fa207..2cbd97f71984013882f2b80b54dcbc33c6a5d364 100644
--- a/tools/gn/variables.cc
+++ b/tools/gn/variables.cc
@@ -574,6 +574,29 @@ const char kConfigs_Help[] =
     "    }\n"
     "  }\n";
 
+const char kConsole[] = "console";
+const char kConsole_HelpShort[] =
+    "console [boolean]: Run this action in the console pool.";
+const char kConsole_Help[] =
+    "console: Run this action in the console pool.\n"
+    "\n"
+    "  Boolean. Defaults to false.\n"
+    "\n"
+    "  Actions marked \"console = true\" will be run in the built-in ninja\n"
+    "  \"console\" pool. They will have access to real stdin and stdout, and\n"
+    "  output will not be buffered by ninja. This can be useful for\n"
+    "  long-running actions with progress logs, or actions that require user \n"
+    "  input.\n"
+    "\n"
+    "  Only one console pool target can run at any one time in Ninja. Refer\n"
+    "  to the Ninja documentation on the console pool for more info.\n"
+    "\n"
+    "Example\n"
+    "\n"
+    "  action(\"long_action_with_progress_logs\") {\n"
+    "    console = true\n"
+    "  }\n";
+
 const char kData[] = "data";
 const char kData_HelpShort[] =
     "data: [file list] Runtime data file dependencies.";
@@ -1249,6 +1272,7 @@ const VariableInfoMap& GetTargetVariables() {
     INSERT_VARIABLE(CheckIncludes)
     INSERT_VARIABLE(CompleteStaticLib)
     INSERT_VARIABLE(Configs)
+    INSERT_VARIABLE(Console)
     INSERT_VARIABLE(Data)
     INSERT_VARIABLE(DataDeps)
     INSERT_VARIABLE(Defines)