Initialize Linux Aura accessibility on the file thread.

It's a part of larger task to move the whole initialization
on the separate thread. Previous CL introduced some hard to
track issues and broke some perf bots. This CL is first part
to make sure bots are fine. It moves gconf related
initialization on the file thread.

BUG=472183, 468989, 468112

Review URL: https://codereview.chromium.org/1640273002

Cr-Commit-Position: refs/heads/master@{#372074}

ui/accessibility/platform/atk_util_auralinux.cc

@@ -8,7 +8,9 @@
 #endif
 #include <glib-2.0/gmodule.h>
 
+#include "base/bind.h"
 #include "base/files/file_path.h"
+#include "base/location.h"
 #include "base/logging.h"
 #include "base/memory/singleton.h"
 #include "ui/accessibility/platform/atk_util_auralinux.h"
@@ -16,41 +18,42 @@
 
 namespace {
 
-#if defined(USE_GCONF)
+typedef void (*gnome_accessibility_module_init)();
 
-const char kGnomeAccessibilityEnabledKey[] =
-    "/desktop/gnome/interface/accessibility";
+const char kAtkBridgePath[] = "gtk-2.0/modules/libatk-bridge.so";
+const char kAtkBridgeSymbolName[] = "gnome_accessibility_module_init";
 
-bool ShouldEnableAccessibility() {
-  GConfClient* client = gconf_client_get_default();
-  if (!client) {
-    LOG(ERROR) << "gconf_client_get_default failed";
+gnome_accessibility_module_init g_accessibility_module_init = nullptr;
+
+bool AccessibilityModuleInitOnFileThread() {
+  // Try to load libatk-bridge.so.
+  base::FilePath atk_bridge_path(ATK_LIB_DIR);
+  atk_bridge_path = atk_bridge_path.Append(kAtkBridgePath);
+  GModule* bridge = g_module_open(atk_bridge_path.value().c_str(),
+                                  static_cast<GModuleFlags>(0));
+  if (!bridge) {
+    VLOG(1) << "Unable to open module " << atk_bridge_path.value();
     return false;
   }
 
-  GError* error = nullptr;
-  gboolean value = gconf_client_get_bool(client,
-                                         kGnomeAccessibilityEnabledKey,
-                                         &error);
-  if (error) {
-    VLOG(1) << "gconf_client_get_bool failed";
-    g_error_free(error);
-    g_object_unref(client);
+  if (!g_module_symbol(bridge, kAtkBridgeSymbolName,
+                      (gpointer *)&g_accessibility_module_init)) {
+    VLOG(1) << "Unable to get symbol pointer from " << atk_bridge_path.value();
+    // Just to make sure it's null;
+    g_accessibility_module_init = nullptr;
     return false;
   }
 
-  g_object_unref(client);
-  return value;
+  return true;
 }
 
-#else  // !defined(USE_GCONF)
+#if defined(USE_GCONF)
 
-bool ShouldEnableAccessibility() {
-  // TODO(k.czech): implement this for non-GNOME desktops.
-  return false;
-}
+const char kAccessibilityEnabled[] = "ACCESSIBILITY_ENABLED";
+const char kGnomeAccessibilityEnabledKey[] =
+    "/desktop/gnome/interface/accessibility";
 
-#endif  // defined(USE_GCONF)
+#endif
 
 }  // namespace
 
@@ -139,44 +142,88 @@ AtkUtilAuraLinux* AtkUtilAuraLinux::GetInstance() {
   return base::Singleton<AtkUtilAuraLinux>::get();
 }
 
+#if defined(USE_GCONF)
+
+AtkUtilAuraLinux::AtkUtilAuraLinux()
+    : is_enabled_(false) {
+}
+
+#else
+
 AtkUtilAuraLinux::AtkUtilAuraLinux() {
 }
 
+#endif // defined(USE_GCONF)
+
 void AtkUtilAuraLinux::Initialize(
-    scoped_refptr<base::TaskRunner> /* init_task_runner */) {
-  // TODO(k.czech): use |init_task_runner| to post a task to do the
-  // initialization rather than doing it on this thread.
-  // http://crbug.com/468112
+    scoped_refptr<base::TaskRunner> init_task_runner) {
 
   // Register our util class.
   g_type_class_unref(g_type_class_ref(ATK_UTIL_AURALINUX_TYPE));
 
-  if (!ShouldEnableAccessibility()) {
-    VLOG(1) << "Will not enable ATK accessibility support.";
-    return;
+  init_task_runner->PostTaskAndReply(
+      FROM_HERE,
+      base::Bind(
+          &AtkUtilAuraLinux::CheckIfAccessibilityIsEnabledOnFileThread,
+          base::Unretained(this)),
+      base::Bind(
+          &AtkUtilAuraLinux::FinishAccessibilityInitOnUIThread,
+          base::Unretained(this)));
+}
+
+AtkUtilAuraLinux::~AtkUtilAuraLinux() {
+}
+
+#if defined(USE_GCONF)
+
+void AtkUtilAuraLinux::CheckIfAccessibilityIsEnabledOnFileThread() {
+  char* enable_accessibility = getenv(kAccessibilityEnabled);
+  if ((enable_accessibility && atoi(enable_accessibility) == 1) ||
+      CheckPlatformAccessibilitySupportOnFileThread())
+    is_enabled_ = AccessibilityModuleInitOnFileThread();
+}
+
+bool AtkUtilAuraLinux::CheckPlatformAccessibilitySupportOnFileThread() {
+  GConfClient* client = gconf_client_get_default();
+  if (!client) {
+    LOG(ERROR) << "gconf_client_get_default failed";
+    return false;
   }
 
-  VLOG(1) << "Enabling ATK accessibility support.";
+  GError* error = nullptr;
+  bool is_enabled = gconf_client_get_bool(client,
+                                    kGnomeAccessibilityEnabledKey,
+                                    &error);
 
-  // Try to load libatk-bridge.so.
-  base::FilePath atk_bridge_path(ATK_LIB_DIR);
-  atk_bridge_path = atk_bridge_path.Append("gtk-2.0/modules/libatk-bridge.so");
-  GModule* bridge = g_module_open(atk_bridge_path.value().c_str(),
-                                  static_cast<GModuleFlags>(0));
-  if (!bridge) {
-    VLOG(1) << "Unable to open module " << atk_bridge_path.value();
-    return;
+  g_object_unref(client);
+
+  if (error) {
+    VLOG(1) << "gconf_client_get_bool failed";
+    g_error_free(error);
+    return false;
   }
 
-  // Try to call gnome_accessibility_module_init from libatk-bridge.so.
-  void (*gnome_accessibility_module_init)();
-  if (g_module_symbol(bridge, "gnome_accessibility_module_init",
-                      (gpointer *)&gnome_accessibility_module_init)) {
-    (*gnome_accessibility_module_init)();
+  return is_enabled;
+}
+
+void AtkUtilAuraLinux::FinishAccessibilityInitOnUIThread() {
+  if (!is_enabled_) {
+    VLOG(1) << "Will not enable ATK accessibility support.";
+    return;
   }
+
+  DCHECK(g_accessibility_module_init);
+  g_accessibility_module_init();
 }
 
-AtkUtilAuraLinux::~AtkUtilAuraLinux() {
+#else
+
+void AtkUtilAuraLinux::CheckIfAccessibilityIsEnabledOnFileThread() {
+}
+
+void AtkUtilAuraLinux::FinishAccessibilityInitOnUIThread() {
 }
 
+#endif // defined(USE_GCONF)
+
 }  // namespace ui

ui/accessibility/platform/atk_util_auralinux.h

@@ -29,6 +29,14 @@ class AtkUtilAuraLinux {
 
  private:
   friend struct base::DefaultSingletonTraits<AtkUtilAuraLinux>;
+
+  void CheckIfAccessibilityIsEnabledOnFileThread();
+  bool CheckPlatformAccessibilitySupportOnFileThread();
+  void FinishAccessibilityInitOnUIThread();
+
+#if defined(USE_GCONF)
+  bool is_enabled_;
+#endif
 };
 
 }  // namespace ui