Add dependency from //headless:gen_devtools_client_api to :protocol_s…

…ources

At least types_inspector.h generated by gen_devtools_client_api needs
base_string_adapter.h generated by protocol_sources. The dependency
ensures that we generate base_string_adapter.h before generating
and compiling types_inspector.cc.

Previously without the dependency, some CL [1] failed to compile on
some bots [2].

[1] https://chromium-review.googlesource.com/c/chromium/src/+/3312656/3
[2] https://cr-buildbucket.appspot.com/build/8828631760542807537

Bug: 1277317
Change-Id: I7a0d7e21f70b230c7bcaddbb9872a8d95136c9a2
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3316146
Reviewed-by: Andrey Kosyakov <caseq@chromium.org>
Commit-Queue: Xianzhu Wang <wangxianzhu@chromium.org>
Cr-Commit-Position: refs/heads/main@{#948788}

headless/BUILD.gn

@@ -187,7 +187,10 @@ foreach(domain, devtools_domains) {
 
 action("gen_devtools_client_api") {
   script = "lib/browser/devtools_api/client_api_generator.py"
-  deps = [ "//third_party/blink/public/devtools_protocol:protocol_version" ]
+  deps = [
+    ":protocol_sources",
+    "//third_party/blink/public/devtools_protocol:protocol_version",
+  ]
   inputs = [
     "$root_gen_dir/third_party/blink/public/devtools_protocol/protocol.json",
   ]
@@ -229,7 +232,10 @@ if (headless_fontconfig_utils && !is_fuchsia) {
 }
 
 inspector_protocol_generate("protocol_sources") {
-  visibility = [ "//headless:backend_cdp_bindings" ]
+  visibility = [
+    ":backend_cdp_bindings",
+    ":gen_devtools_client_api",
+  ]
   deps = [ "//third_party/blink/public/devtools_protocol:protocol_version" ]
   _blink_protocol_path = rebase_path(
           "$root_gen_dir/third_party/blink/public/devtools_protocol/protocol.json",