Only generate GPU json data entries related to a given platform at build time.

gpu/config/BUILD.gn

Index: gpu/config/BUILD.gn
diff --git a/gpu/config/BUILD.gn b/gpu/config/BUILD.gn
index f8d7af043996fe3745b0ae2e29969e3a807364a6..1a980afd8b20e4e846fea3c74a9b55f33f42190d 100644
--- a/gpu/config/BUILD.gn
+++ b/gpu/config/BUILD.gn
@@ -55,7 +55,19 @@ action("process_json") {
     "--output-dir",
     rebase_path("$target_gen_dir", root_build_dir),
     "--skip-testing-data",
+    "--os-filter",
   ]
+  if (is_win) {
+    args += [ "win" ]
+  } else if (is_mac) {
+    args += [ "macosx" ]
+  } else if (is_android) {
+    args += [ "android" ]
+  } else if (is_chromeos) {
+    args += [ "chromeos" ]
+  } else {
+    args += [ "linux" ]
+  }
 }
 
 source_set("config_sources") {