[fuchsia] Add build flag to enable remote debugging in WebRunner.

Bug: 1016036
Change-Id: I9c2125d7b2fe11c08f7fa7024155ae25f4a0360e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1898713Reviewed-by: Wez <wez@chromium.org>
Commit-Queue: Fabrice de Gans-Riberi <fdegans@chromium.org>
Cr-Commit-Position: refs/heads/master@{#712396}

fuchsia/runners/BUILD.gn

@@ -14,11 +14,17 @@ declare_args() {
   # TODO(crbug.com/1000858): Revisit this value once hardware playback is fixed
   #                          (fxb/13659).
   enable_software_video_decoders = true
+
+  # Set to a non-zero value to enable remote debugging on that port in WebRunner.
+  web_runner_remote_debugging_port = 0
 }
 
 buildflag_header("buildflags") {
   header = "buildflags.h"
-  flags = [ "ENABLE_SOFTWARE_VIDEO_DECODERS=$enable_software_video_decoders" ]
+  flags = [
+    "ENABLE_SOFTWARE_VIDEO_DECODERS=$enable_software_video_decoders",
+    "WEB_RUNNER_REMOTE_DEBUGGING_PORT=$web_runner_remote_debugging_port",
+  ]
   visibility = [ ":*" ]
 }
 
@@ -31,6 +37,7 @@ source_set("common") {
     "common/web_content_runner.h",
   ]
   deps = [
+    ":buildflags",
     "//base",
     "//fuchsia/base",
     "//fuchsia/base:modular",

fuchsia/runners/common/web_content_runner.cc

@@ -18,6 +18,7 @@
 #include "base/fuchsia/scoped_service_binding.h"
 #include "base/fuchsia/startup_context.h"
 #include "base/logging.h"
+#include "fuchsia/runners/buildflags.h"
 #include "fuchsia/runners/common/web_component.h"
 #include "url/gurl.h"
 
@@ -54,10 +55,17 @@ fuchsia::web::ContextPtr WebContentRunner::CreateWebContext(
 // static
 fuchsia::web::ContextPtr WebContentRunner::CreateDefaultWebContext(
     fuchsia::web::ContextFeatureFlags features) {
-  return CreateWebContext(BuildCreateContextParams(
-      OpenDirectoryOrFail(
-          base::FilePath(base::fuchsia::kPersistedDataDirectoryPath)),
-      features));
+  fuchsia::web::CreateContextParams create_context_params =
+      BuildCreateContextParams(OpenDirectoryOrFail(base::FilePath(
+                                   base::fuchsia::kPersistedDataDirectoryPath)),
+                               features);
+
+  if (BUILDFLAG(WEB_RUNNER_REMOTE_DEBUGGING_PORT) != 0) {
+    create_context_params.set_remote_debugging_port(
+        BUILDFLAG(WEB_RUNNER_REMOTE_DEBUGGING_PORT));
+  }
+
+  return CreateWebContext(std::move(create_context_params));
 }
 
 // static
@@ -114,6 +122,8 @@ void WebContentRunner::StartComponent(
       this,
       std::make_unique<base::fuchsia::StartupContext>(std::move(startup_info)),
       std::move(controller_request));
+  if (BUILDFLAG(WEB_RUNNER_REMOTE_DEBUGGING_PORT) != 0)
+    component->EnableRemoteDebugging();
   component->StartComponent();
   component->LoadUrl(url, std::vector<fuchsia::net::http::Header>());
   RegisterComponent(std::move(component));