Unbundle openh264

build/shim_headers.gni

Index: build/shim_headers.gni
diff --git a/build/shim_headers.gni b/build/shim_headers.gni
index a37bd4a1d8d72a5448b23d2f26549acd82e2525d..56591484d1c0cd43d13993277542c2ae083a875e 100644
--- a/build/shim_headers.gni
+++ b/build/shim_headers.gni
@@ -14,12 +14,19 @@ template("shim_headers") {
   action(action_name) {
     script = "//tools/generate_shim_headers/generate_shim_headers.py"
     args = [
-             "--generate",
-             "--headers-root",
-             rebase_path(invoker.root_path),
-             "--output-directory",
-             rebase_path(shim_headers_path),
-           ] + invoker.headers
+      "--generate",
+      "--headers-root",
+      rebase_path(invoker.root_path),
+      "--output-directory",
+      rebase_path(shim_headers_path),
+    ]
+    if (defined(invoker.prefix)) {
+      args += [
+        "--prefix",
+        invoker.prefix,
+      ]
+    }
+    args += invoker.headers
 
     outputs = process_file_template(invoker.headers,
                                     "${shim_headers_path}/{{source_file_part}}")