Allow ash-chrome to launch lacros-chrome when running on linux

This allows working on mojo connections without deploying both binaries
to a device.

* Avoid DCHECK when calling lacros_process_.Pid() on a null process
  handle
* Forward ash-chrome's XDG_RUNTIME_DIR because on linux we can't
  write to /run/chrome
* Use a subdir of the ash-chrome user-data-dir instead of a
  hard-coded path

You can now launch lacros-chrome via the shelf icon if you run
ash-chrome like this:
XDG_RUNTIME_DIR=/tmp/ash_chrome_xdg_runtime ./out/Default/chrome --user-data-dir=/tmp/chrome --enable-wayland-server --no-startup-window --login-manager --enable-features=LacrosSupport --lacros-chrome-path=/w/chrome/src/out/LacrosDesktop

Bug: none
Change-Id: I94a5319174b5952cb6605bf2243821e51ae30ebf
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2255032
Commit-Queue: James Cook <jamescook@chromium.org>
Reviewed-by: Hidehiko Abe <hidehiko@chromium.org>
Cr-Commit-Position: refs/heads/master@{#780909}

chrome/browser/chromeos/lacros/lacros_loader.cc

@@ -8,6 +8,7 @@
 
 #include "base/bind.h"
 #include "base/command_line.h"
+#include "base/files/file_path.h"
 #include "base/files/file_util.h"
 #include "base/logging.h"
 #include "base/task/task_traits.h"
@@ -34,7 +35,7 @@ bool CheckInstalledAndMaybeRemoveUserDirectory(
   // shuts down during the directory remove, some partially-removed directory
   // may be kept, and if the user flips the flag in the next time, that
   // partially-removed directory could be used. Fix this.
-  base::DeleteFileRecursively(base::FilePath(lacros_util::kUserDataDir));
+  base::DeleteFileRecursively(lacros_util::GetUserDataDir());
   return true;
 }
 

chrome/browser/chromeos/lacros/lacros_manager.cc

@@ -10,7 +10,9 @@
 
 #include "base/bind.h"
 #include "base/command_line.h"
+#include "base/environment.h"
 #include "base/files/file.h"
+#include "base/files/file_path.h"
 #include "base/files/file_util.h"
 #include "base/logging.h"
 #include "base/metrics/user_metrics.h"
@@ -36,7 +38,7 @@ namespace {
 LacrosManager* g_instance = nullptr;
 
 base::FilePath LacrosLogPath() {
-  return base::FilePath(lacros_util::kUserDataDir).Append("lacros.log");
+  return lacros_util::GetUserDataDir().Append("lacros.log");
 }
 
 // TODO(https://crbug.com/1091863): This logic is not robust against the
@@ -82,6 +84,17 @@ bool StartBackground(base::ProcessId pid, const base::FilePath& lacros_path) {
   return already_running;
 }
 
+std::string GetXdgRuntimeDir() {
+  // If ash-chrome was given an environment variable, use it.
+  std::unique_ptr<base::Environment> env = base::Environment::Create();
+  std::string xdg_runtime_dir;
+  if (env->GetVar("XDG_RUNTIME_DIR", &xdg_runtime_dir))
+    return xdg_runtime_dir;
+
+  // Otherwise provide the default for Chrome OS devices.
+  return "/run/chrome";
+}
+
 }  // namespace
 
 // static
@@ -139,9 +152,10 @@ void LacrosManager::Start() {
   scoped_refptr<base::SequencedTaskRunner> task_runner =
       base::ThreadPool::CreateSequencedTaskRunner(
           {base::MayBlock(), base::TaskShutdownBehavior::SKIP_ON_SHUTDOWN});
+  base::ProcessId pid =
+      lacros_process_.IsValid() ? lacros_process_.Pid() : base::kNullProcessId;
   task_runner->PostTaskAndReplyWithResult(
-      FROM_HERE,
-      base::BindOnce(&StartBackground, lacros_process_.Pid(), lacros_path_),
+      FROM_HERE, base::BindOnce(&StartBackground, pid, lacros_path_),
       base::BindOnce(&LacrosManager::StartForeground,
                      weak_factory_.GetWeakPtr()));
 }
@@ -154,7 +168,7 @@ void LacrosManager::StartForeground(bool already_running) {
 
   base::LaunchOptions options;
   options.environment["EGL_PLATFORM"] = "surfaceless";
-  options.environment["XDG_RUNTIME_DIR"] = "/run/chrome";
+  options.environment["XDG_RUNTIME_DIR"] = GetXdgRuntimeDir();
 
   std::string api_key;
   if (google_apis::HasAPIKeyConfigured())
@@ -169,14 +183,16 @@ void LacrosManager::StartForeground(bool already_running) {
 
   options.kill_on_parent_death = true;
 
-  std::vector<std::string> argv = {
-      chrome_path,
-      "--ozone-platform=wayland",
-      std::string("--user-data-dir=") + lacros_util::kUserDataDir,
-      "--enable-gpu-rasterization",
-      "--enable-oop-rasterization",
-      "--lang=en-US",
-      "--enable-crashpad"};
+  // Paths are UTF-8 safe on Chrome OS.
+  std::string user_data_dir = lacros_util::GetUserDataDir().AsUTF8Unsafe();
+
+  std::vector<std::string> argv = {chrome_path,
+                                   "--ozone-platform=wayland",
+                                   "--user-data-dir=" + user_data_dir,
+                                   "--enable-gpu-rasterization",
+                                   "--enable-oop-rasterization",
+                                   "--lang=en-US",
+                                   "--enable-crashpad"};
 
   // We assume that if there's a custom chrome path, that this is a developer
   // and they want to enable logging.

chrome/browser/chromeos/lacros/lacros_util.cc

@@ -4,8 +4,11 @@
 
 #include "chrome/browser/chromeos/lacros/lacros_util.h"
 
+#include "base/files/file_path.h"
+#include "base/path_service.h"
 #include "base/strings/string_util.h"
 #include "chrome/common/channel_info.h"
+#include "chrome/common/chrome_paths.h"
 #include "components/user_manager/user.h"
 #include "components/user_manager/user_manager.h"
 #include "components/user_manager/user_type.h"
@@ -38,7 +41,12 @@ bool IsUserTypeAllowed(const User* user) {
 
 }  // namespace
 
-constexpr char kUserDataDir[] = "/home/chronos/user/lacros";
+base::FilePath GetUserDataDir() {
+  // Return a subdirectory "lacros" inside of the ash-chrome user data dir.
+  base::FilePath path;
+  base::PathService::Get(chrome::DIR_USER_DATA, &path);
+  return path.Append("lacros");
+}
 
 bool IsLacrosAllowed() {
   return IsLacrosAllowed(chrome::GetChannel());

chrome/browser/chromeos/lacros/lacros_util.h

@@ -5,14 +5,18 @@
 #ifndef CHROME_BROWSER_CHROMEOS_LACROS_LACROS_UTIL_H_
 #define CHROME_BROWSER_CHROMEOS_LACROS_LACROS_UTIL_H_
 
+namespace base {
+class FilePath;
+}  // namespace base
+
 namespace version_info {
 enum class Channel;
 }  // namespace version_info
 
 namespace lacros_util {
 
-// Path of the user directory for lacros-chrome.
-extern const char kUserDataDir[];
+// Returns the user directory for lacros-chrome.
+base::FilePath GetUserDataDir();
 
 // Returns true if lacros is allowed for the current user type, chrome channel,
 // etc.