Add kAccessibilityFocusFallsbackToWidget property

- Added kAccessibilityFocusFallsbackToWidget property to aura::Window.
- Default value of kAccessibilityFocusFallsbackToWidget is true.
- kAccessibilityFocusFallsbackToWidget is set to false for arc window.

BUG=661061
TEST=manually tested as described in the issue; User can navigate
     elements in Android window by using TalkBack.
     interactive_ui_tests:SpokenFeedbackTest

Review-Url: https://codereview.chromium.org/2530073002
Cr-Commit-Position: refs/heads/master@{#437469}

chrome/browser/chromeos/accessibility/spoken_feedback_browsertest.cc

@@ -500,7 +500,11 @@ IN_PROC_BROWSER_TEST_P(SpokenFeedbackTest, OverviewMode) {
       break;
   }
 
-  EXPECT_EQ("Entered window overview mode", speech_monitor_.GetNextUtterance());
+  while (true) {
+    std::string utterance = speech_monitor_.GetNextUtterance();
+    if (utterance == "Entered window overview mode")
+      break;
+  }
 
   SendKeyPress(ui::VKEY_TAB);
   // On Chrome OS accessibility title for tabbed browser windows contains app
@@ -534,9 +538,12 @@ IN_PROC_BROWSER_TEST_P(SpokenFeedbackTest, MAYBE_ChromeVoxShiftSearch) {
 
   // Press Search+/ to enter ChromeVox's "find in page".
   SendKeyPressWithSearch(ui::VKEY_OEM_2);
-  EXPECT_EQ(", window", speech_monitor_.GetNextUtterance());
-  EXPECT_EQ("webView", speech_monitor_.GetNextUtterance());
-  EXPECT_EQ("Find in page.", speech_monitor_.GetNextUtterance());
+
+  while (true) {
+    std::string utterance = speech_monitor_.GetNextUtterance();
+    if (utterance == "Find in page.")
+      break;
+  }
 }
 
 #if defined(MEMORY_SANITIZER)

components/exo/shell_surface.cc

@@ -1076,6 +1076,8 @@ void ShellSurface::CreateShellSurfaceWidget(ui::WindowShowState show_state) {
 
   aura::Window* window = widget_->GetNativeWindow();
   window->SetName("ExoShellSurface");
+  window->SetProperty(aura::client::kAccessibilityFocusFallsbackToWidgetKey,
+                      false);
   window->AddChild(surface_->window());
   window->SetEventTargeter(base::WrapUnique(new CustomWindowTargeter(widget_)));
   SetApplicationId(window, application_id_);

ui/aura/client/aura_constants.cc

@@ -27,6 +27,7 @@ namespace client {
 
 // Alphabetical sort.
 
+DEFINE_WINDOW_PROPERTY_KEY(bool, kAccessibilityFocusFallsbackToWidgetKey, true);
 DEFINE_WINDOW_PROPERTY_KEY(bool, kAlwaysOnTopKey, false);
 DEFINE_WINDOW_PROPERTY_KEY(bool, kAnimationsDisabledKey, false);
 DEFINE_OWNED_WINDOW_PROPERTY_KEY(gfx::ImageSkia, kAppIconKey, nullptr);

ui/aura/client/aura_constants.h

@@ -24,6 +24,11 @@ namespace client {
 
 // Alphabetical sort.
 
+// A property key to store whether accessibility focus falls back to widget or
+// not.
+AURA_EXPORT extern const WindowProperty<bool>* const
+    kAccessibilityFocusFallsbackToWidgetKey;
+
 // A property key to store always-on-top flag.
 AURA_EXPORT extern const WindowProperty<bool>* const kAlwaysOnTopKey;
 

ui/views/accessibility/ax_aura_obj_cache.cc

@@ -6,6 +6,8 @@
 
 #include "base/memory/ptr_util.h"
 #include "base/memory/singleton.h"
+#include "base/strings/string_util.h"
+#include "ui/aura/client/aura_constants.h"
 #include "ui/aura/client/focus_client.h"
 #include "ui/aura/window.h"
 #include "ui/views/accessibility/ax_aura_obj_wrapper.h"
@@ -160,8 +162,14 @@ View* AXAuraObjCache::GetFocusedView() {
   View* focused_view = focus_manager->GetFocusedView();
   if (focused_view)
     return focused_view;
-  else
+
+  if (focused_window->GetProperty(
+          aura::client::kAccessibilityFocusFallsbackToWidgetKey)) {
+    // If no view is focused, falls back to root view.
     return focused_widget->GetRootView();
+  }
+
+  return nullptr;
 }
 
 void AXAuraObjCache::OnWindowFocused(aura::Window* gained_focus,