Enable -Wunreachable-code in Fuchsia builds.

Depends on https://chromium-review.googlesource.com/c/angle/angle/+/2112281

Bug: 346399
Change-Id: I6bf27dc15303c207be0ae85dd3256af217db005b
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2111833Reviewed-by: Sergey Ulanov <sergeyu@chromium.org>
Commit-Queue: Nico Weber <thakis@chromium.org>
Cr-Commit-Position: refs/heads/master@{#752299}

build/config/compiler/BUILD.gn

@@ -1591,7 +1591,8 @@ config("chromium_code") {
 
     # TODO(thakis): Enable this more often, https://crbug.com/346399
     # use_libfuzzer: https://crbug.com/1063180
-    if (!is_nacl && target_os == "linux" && !use_libfuzzer) {
+    if (!is_nacl && !use_libfuzzer &&
+        (target_os == "fuchsia" || target_os == "linux")) {
       cflags += [ "-Wunreachable-code" ]
     }
 

fuchsia/runners/common/web_content_runner.cc

@@ -74,8 +74,9 @@ 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)
+#if BUILDFLAG(WEB_RUNNER_REMOTE_DEBUGGING_PORT) != 0
   component->EnableRemoteDebugging();
+#endif
   component->StartComponent();
   component->LoadUrl(url, std::vector<fuchsia::net::http::Header>());
   RegisterComponent(std::move(component));

fuchsia/runners/web/main.cc

@@ -42,10 +42,10 @@ int main(int argc, char** argv) {
       base::FilePath(base::fuchsia::kPersistedDataDirectoryPath)));
   CHECK(create_context_params.data_directory());
 
-  if (BUILDFLAG(WEB_RUNNER_REMOTE_DEBUGGING_PORT) != 0) {
+#if BUILDFLAG(WEB_RUNNER_REMOTE_DEBUGGING_PORT) != 0
   create_context_params.set_remote_debugging_port(
       BUILDFLAG(WEB_RUNNER_REMOTE_DEBUGGING_PORT));
-  }
+#endif
 
   WebContentRunner runner(
       std::move(create_context_params),

third_party/blink/renderer/platform/scheduler/common/thread_cpu_throttler.cc

@@ -167,15 +167,16 @@ void ThreadCPUThrottler::ThrottlingThread::Throttle() {
 }
 
 void ThreadCPUThrottler::ThrottlingThread::Start() {
-#ifdef USE_SIGNALS
+#if defined(USE_SIGNALS) || defined(OS_WIN)
+#if defined(USE_SIGNALS)
   InstallSignalHandler();
-#elif !defined(OS_WIN)
-  LOG(ERROR) << "CPU throttling is not supported.";
-  return;
 #endif
   if (!base::PlatformThread::Create(0, this, &throttling_thread_handle_)) {
     LOG(ERROR) << "Failed to create throttling thread.";
   }
+#else
+  LOG(ERROR) << "CPU throttling is not supported.";
+#endif
 }
 
 void ThreadCPUThrottler::ThrottlingThread::Sleep(base::TimeDelta duration) {