ChildProcessLauncher without BrowserThread

This removes ChildProcessLauncher's nominal dependency on BrowserThread
initialization by capturing the client's current SequencedTaskRunner
rather than the current thread's BrowserThread::ID, which may not be
initialized yet.

Bug: 989769
Change-Id: Ia4b9cb0781540f6737be761c201b6440f7713ac6
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1731473Reviewed-by: John Abd-El-Malek <jam@chromium.org>
Reviewed-by: Clark DuVall <cduvall@chromium.org>
Commit-Queue: Ken Rockot <rockot@google.com>
Cr-Commit-Position: refs/heads/master@{#683390}

content/browser/child_process_launcher.cc

@@ -49,11 +49,10 @@ ChildProcessLauncher::ChildProcessLauncher(
 #endif
 {
   DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
-  CHECK(BrowserThread::GetCurrentThreadIdentifier(&client_thread_id_));
 
-  helper_ = new ChildProcessLauncherHelper(
-      child_process_id, client_thread_id_, std::move(command_line),
-      std::move(delegate), weak_factory_.GetWeakPtr(), terminate_on_shutdown,
+  helper_ = base::MakeRefCounted<ChildProcessLauncherHelper>(
+      child_process_id, std::move(command_line), std::move(delegate),
+      weak_factory_.GetWeakPtr(), terminate_on_shutdown,
 #if defined(OS_ANDROID)
       client_->CanUseWarmUpConnection(),
 #endif

content/browser/child_process_launcher.h

@@ -226,7 +226,6 @@ class CONTENT_EXPORT ChildProcessLauncher {
               int error_code);
 
   Client* client_;
-  BrowserThread::ID client_thread_id_;
 
   // The process associated with this ChildProcessLauncher. Set in Notify by
   // ChildProcessLauncherHelper once the process was started.

content/browser/child_process_launcher_helper.cc

@@ -13,6 +13,7 @@
 #include "base/task/post_task.h"
 #include "base/task/single_thread_task_runner_thread_mode.h"
 #include "base/task/task_traits.h"
+#include "base/threading/sequenced_task_runner_handle.h"
 #include "content/browser/child_process_launcher.h"
 #include "content/public/browser/browser_task_traits.h"
 #include "content/public/browser/child_process_launcher_utils.h"
@@ -66,7 +67,6 @@ ChildProcessLauncherHelper::Process::Process::operator=(
 
 ChildProcessLauncherHelper::ChildProcessLauncherHelper(
     int child_process_id,
-    BrowserThread::ID client_thread_id,
     std::unique_ptr<base::CommandLine> command_line,
     std::unique_ptr<SandboxedProcessLauncherDelegate> delegate,
     const base::WeakPtr<ChildProcessLauncher>& child_process_launcher,
@@ -77,7 +77,7 @@ ChildProcessLauncherHelper::ChildProcessLauncherHelper(
     mojo::OutgoingInvitation mojo_invitation,
     const mojo::ProcessErrorCallback& process_error_callback)
     : child_process_id_(child_process_id),
-      client_thread_id_(client_thread_id),
+      client_task_runner_(base::SequencedTaskRunnerHandle::Get()),
       command_line_(std::move(command_line)),
       delegate_(std::move(delegate)),
       child_process_launcher_(child_process_launcher),
@@ -94,7 +94,7 @@ ChildProcessLauncherHelper::ChildProcessLauncherHelper(
 ChildProcessLauncherHelper::~ChildProcessLauncherHelper() = default;
 
 void ChildProcessLauncherHelper::StartLaunchOnClientThread() {
-  DCHECK_CURRENTLY_ON(client_thread_id_);
+  DCHECK(client_task_runner_->RunsTasksInCurrentSequence());
 
   BeforeLaunchOnClientThread();
 
@@ -173,8 +173,8 @@ void ChildProcessLauncherHelper::PostLaunchOnLauncherThread(
     }
   }
 
-  base::PostTaskWithTraits(
-      FROM_HERE, {client_thread_id_},
+  client_task_runner_->PostTask(
+      FROM_HERE,
       base::BindOnce(&ChildProcessLauncherHelper::PostLaunchOnClientThread,
                      this, std::move(process), launch_result));
 }

content/browser/child_process_launcher_helper.h

@@ -10,11 +10,12 @@
 
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
+#include "base/memory/weak_ptr.h"
 #include "base/optional.h"
 #include "base/process/kill.h"
 #include "base/process/process.h"
+#include "base/sequenced_task_runner.h"
 #include "build/build_config.h"
-#include "content/public/browser/browser_thread.h"
 #include "content/public/common/result_codes.h"
 #include "mojo/public/cpp/platform/platform_channel.h"
 #include "mojo/public/cpp/system/invitation.h"
@@ -93,7 +94,6 @@ class ChildProcessLauncherHelper :
 
   ChildProcessLauncherHelper(
       int child_process_id,
-      BrowserThread::ID client_thread_id,
       std::unique_ptr<base::CommandLine> command_line,
       std::unique_ptr<SandboxedProcessLauncherDelegate> delegate,
       const base::WeakPtr<ChildProcessLauncher>& child_process_launcher,
@@ -161,8 +161,6 @@ class ChildProcessLauncherHelper :
   void PostLaunchOnClientThread(ChildProcessLauncherHelper::Process process,
                                 int error_code);
 
-  int client_thread_id() const { return client_thread_id_; }
-
   // See ChildProcessLauncher::GetChildTerminationInfo for more info.
   ChildProcessTerminationInfo GetTerminationInfo(
       const ChildProcessLauncherHelper::Process& process,
@@ -221,7 +219,7 @@ class ChildProcessLauncherHelper :
 #endif
 
   const int child_process_id_;
-  const BrowserThread::ID client_thread_id_;
+  const scoped_refptr<base::SequencedTaskRunner> client_task_runner_;
   base::TimeTicks begin_launch_time_;
   std::unique_ptr<base::CommandLine> command_line_;
   std::unique_ptr<SandboxedProcessLauncherDelegate> delegate_;

content/browser/child_process_launcher_helper_android.cc

@@ -140,8 +140,8 @@ ChildProcessLauncherHelper::LaunchProcessOnLauncherThread(
       env, reinterpret_cast<intptr_t>(this), j_argv, j_file_infos,
       can_use_warm_up_connection));
   AddRef();  // Balanced by OnChildProcessStarted.
-  base::PostTaskWithTraits(
-      FROM_HERE, {client_thread_id_},
+  client_task_runner_->PostTask(
+      FROM_HERE,
       base::BindOnce(
           &ChildProcessLauncherHelper::set_java_peer_available_on_client_thread,
           this));

content/browser/child_process_launcher_helper_fuchsia.cc

@@ -48,7 +48,7 @@ void ChildProcessLauncherHelper::ResetRegisteredFilesForTesting() {
 }
 
 void ChildProcessLauncherHelper::BeforeLaunchOnClientThread() {
-  DCHECK_CURRENTLY_ON(client_thread_id_);
+  DCHECK(client_task_runner_->RunsTasksInCurrentSequence());
 
   sandbox_policy_.Initialize(delegate_->GetSandboxType());
 }

content/browser/child_process_launcher_helper_linux.cc

@@ -26,12 +26,12 @@ namespace internal {
 
 base::Optional<mojo::NamedPlatformChannel>
 ChildProcessLauncherHelper::CreateNamedPlatformChannelOnClientThread() {
-  DCHECK_CURRENTLY_ON(client_thread_id_);
+  DCHECK(client_task_runner_->RunsTasksInCurrentSequence());
   return base::nullopt;
 }
 
 void ChildProcessLauncherHelper::BeforeLaunchOnClientThread() {
-  DCHECK_CURRENTLY_ON(client_thread_id_);
+  DCHECK(client_task_runner_->RunsTasksInCurrentSequence());
 }
 
 std::unique_ptr<FileMappedForLaunch>

content/browser/child_process_launcher_helper_mac.cc

@@ -33,12 +33,12 @@ namespace internal {
 
 base::Optional<mojo::NamedPlatformChannel>
 ChildProcessLauncherHelper::CreateNamedPlatformChannelOnClientThread() {
-  DCHECK_CURRENTLY_ON(client_thread_id_);
+  DCHECK(client_task_runner_->RunsTasksInCurrentSequence());
   return base::nullopt;
 }
 
 void ChildProcessLauncherHelper::BeforeLaunchOnClientThread() {
-  DCHECK_CURRENTLY_ON(client_thread_id_);
+  DCHECK(client_task_runner_->RunsTasksInCurrentSequence());
 }
 
 std::unique_ptr<PosixFileDescriptorInfo>

content/browser/child_process_launcher_helper_win.cc

@@ -24,12 +24,12 @@ namespace content {
 namespace internal {
 
 void ChildProcessLauncherHelper::BeforeLaunchOnClientThread() {
-  DCHECK_CURRENTLY_ON(client_thread_id_);
+  DCHECK(client_task_runner_->RunsTasksInCurrentSequence());
 }
 
 base::Optional<mojo::NamedPlatformChannel>
 ChildProcessLauncherHelper::CreateNamedPlatformChannelOnClientThread() {
-  DCHECK_CURRENTLY_ON(client_thread_id_);
+  DCHECK(client_task_runner_->RunsTasksInCurrentSequence());
 
   if (!delegate_->ShouldLaunchElevated())
     return base::nullopt;