Pass a TaskRunner through ViewsDelegate to put AX init on FILE thread

Adds an interface to ViewsDelegate to get a TaskRunner for a thread that
can be used for initialization tasks (implemented using the FILE thread),
and passes that TaskRunner to the ATK accessibility initialization code,
which currently does I/O on the main thread, causing a perf issue.

This change just adds the plumbing to get the TaskRunner there.
This will be followed up by this change that actually moves the initialization
to the other thread: https://codereview.chromium.org/1028553003/

BUG=468112

Review URL: https://codereview.chromium.org/1089003003

Cr-Commit-Position: refs/heads/master@{#327117}

chrome/browser/ui/views/chrome_views_delegate.cc

@@ -14,6 +14,7 @@
 #include "chrome/browser/profiles/profile_manager.h"
 #include "chrome/browser/ui/browser_window_state.h"
 #include "chrome/common/chrome_version_info.h"
+#include "content/public/browser/browser_thread.h"
 #include "content/public/browser/context_factory.h"
 #include "grit/chrome_unscaled_resources.h"
 #include "ui/base/resource/resource_bundle.h"
@@ -388,6 +389,16 @@ std::string ChromeViewsDelegate::GetApplicationName() {
   return chrome::VersionInfo().Name();
 }
 
+#if defined(OS_LINUX) && !defined(OS_CHROMEOS)
+scoped_refptr<base::TaskRunner>
+    ChromeViewsDelegate::GetTaskRunnerForAuraLinuxAccessibilityInit() {
+  // This should be on the FILE thread so that we can open libatk-bridge.so
+  // without blocking.
+  return content::BrowserThread::GetMessageLoopProxyForThread(
+      content::BrowserThread::FILE);
+}
+#endif
+
 #if defined(OS_WIN)
 int ChromeViewsDelegate::GetAppbarAutohideEdges(HMONITOR monitor,
                                                 const base::Closure& callback) {

chrome/browser/ui/views/chrome_views_delegate.h

@@ -49,6 +49,10 @@ class ChromeViewsDelegate : public views::ViewsDelegate {
 #endif
   ui::ContextFactory* GetContextFactory() override;
   std::string GetApplicationName() override;
+#if defined(OS_LINUX) && !defined(OS_CHROMEOS)
+  scoped_refptr<base::TaskRunner>
+      GetTaskRunnerForAuraLinuxAccessibilityInit() override;
+#endif
 #if defined(OS_WIN)
   int GetAppbarAutohideEdges(HMONITOR monitor,
                              const base::Closure& callback) override;

ui/accessibility/platform/atk_util_auralinux.cc

@@ -140,6 +140,14 @@ AtkUtilAuraLinux* AtkUtilAuraLinux::GetInstance() {
 }
 
 AtkUtilAuraLinux::AtkUtilAuraLinux() {
+}
+
+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
+
   // Register our util class.
   g_type_class_unref(g_type_class_ref(ATK_UTIL_AURALINUX_TYPE));
 

ui/accessibility/platform/atk_util_auralinux.h

@@ -8,6 +8,10 @@
 #include "base/memory/singleton.h"
 #include "ui/accessibility/ax_export.h"
 
+namespace base {
+class TaskRunner;
+}
+
 namespace ui {
 
 // This singleton class initializes ATK (accessibility toolkit) and
@@ -21,6 +25,8 @@ class AtkUtilAuraLinux {
   AtkUtilAuraLinux();
   virtual ~AtkUtilAuraLinux();
 
+  void Initialize(scoped_refptr<base::TaskRunner> init_task_runner);
+
  private:
   friend struct DefaultSingletonTraits<AtkUtilAuraLinux>;
 };

ui/accessibility/platform/ax_platform_node_auralinux.cc

@@ -6,6 +6,7 @@
 
 #include "base/command_line.h"
 #include "base/strings/sys_string_conversions.h"
+#include "base/task_runner.h"
 #include "ui/accessibility/ax_node_data.h"
 #include "ui/accessibility/platform/atk_util_auralinux.h"
 #include "ui/accessibility/platform/ax_platform_node_delegate.h"
@@ -287,7 +288,12 @@ AXPlatformNode* AXPlatformNodeAuraLinux::application_ = nullptr;
 // static
 void AXPlatformNodeAuraLinux::SetApplication(AXPlatformNode* application) {
   application_ = application;
-  AtkUtilAuraLinux::GetInstance();
+}
+
+// static
+void AXPlatformNodeAuraLinux::StaticInitialize(
+    scoped_refptr<base::TaskRunner> init_task_runner) {
+  AtkUtilAuraLinux::GetInstance()->Initialize(init_task_runner);
 }
 
 AtkRole AXPlatformNodeAuraLinux::GetAtkRole() {

ui/accessibility/platform/ax_platform_node_auralinux.h

@@ -7,9 +7,14 @@
 
 #include <atk/atk.h>
 
+#include "base/memory/ref_counted.h"
 #include "ui/accessibility/ax_export.h"
 #include "ui/accessibility/platform/ax_platform_node_base.h"
 
+namespace base {
+class TaskRunner;
+}
+
 namespace ui {
 
 // Implements accessibility on Aura Linux using ATK.
@@ -22,6 +27,10 @@ class AXPlatformNodeAuraLinux : public AXPlatformNodeBase {
   AX_EXPORT static void SetApplication(AXPlatformNode* application);
   static AXPlatformNode* application() { return application_; }
 
+  // Do static initialization using the given task runner for file operations.
+  AX_EXPORT static void StaticInitialize(
+      scoped_refptr<base::TaskRunner> init_task_runner);
+
   AtkRole GetAtkRole();
   void GetAtkState(AtkStateSet* state_set);
   void GetAtkRelations(AtkRelationSet* atk_relation_set);

ui/views/accessibility/native_view_accessibility_auralinux.cc

@@ -125,6 +125,13 @@ class AuraLinuxApplication
           ViewsDelegate::views_delegate->GetApplicationName());
     }
     ui::AXPlatformNodeAuraLinux::SetApplication(platform_node_);
+    if (ViewsDelegate::views_delegate) {
+      scoped_refptr<base::TaskRunner> init_task_runner =
+          ViewsDelegate::views_delegate->
+          GetTaskRunnerForAuraLinuxAccessibilityInit();
+      if (init_task_runner)
+        ui::AXPlatformNodeAuraLinux::StaticInitialize(init_task_runner);
+    }
   }
 
   ~AuraLinuxApplication() override {

ui/views/views_delegate.cc

@@ -91,6 +91,13 @@ std::string ViewsDelegate::GetApplicationName() {
   return program.BaseName().AsUTF8Unsafe();
 }
 
+#if defined(OS_LINUX) && !defined(OS_CHROMEOS)
+scoped_refptr<base::TaskRunner>
+    ViewsDelegate::GetTaskRunnerForAuraLinuxAccessibilityInit() {
+  return nullptr;
+}
+#endif
+
 #if defined(OS_WIN)
 int ViewsDelegate::GetAppbarAutohideEdges(HMONITOR monitor,
                                           const base::Closure& callback) {

ui/views/views_delegate.h

@@ -19,6 +19,7 @@
 #include "ui/views/widget/widget.h"
 
 namespace base {
+class TaskRunner;
 class TimeDelta;
 }
 
@@ -138,6 +139,13 @@ class VIEWS_EXPORT ViewsDelegate {
   // Returns the user-visible name of the application.
   virtual std::string GetApplicationName();
 
+#if defined(OS_LINUX) && !defined(OS_CHROMEOS)
+  // Get a task runner suitable for posting initialization tasks for
+  // Aura Linux accessibility.
+  virtual scoped_refptr<base::TaskRunner>
+      GetTaskRunnerForAuraLinuxAccessibilityInit();
+#endif
+
 #if defined(OS_WIN)
   // Starts a query for the appbar autohide edges of the specified monitor and
   // returns the current value.  If the query finds the edges have changed from