[fuchsia] Delay teardown of FrameImpl on accessibility errors

Tear down the Frame by posting a task instead of in the
AccessibilityBridge, by adding OnAccessibilityError.

Bug: 1128954
Change-Id: Iba40229d7e11eb61534ef45fc16326b10814e59a
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2545575
Commit-Queue: Sharon Yang <yangsharon@chromium.org>
Reviewed-by: Sergey Ulanov <sergeyu@chromium.org>
Cr-Commit-Position: refs/heads/master@{#828547}

fuchsia/engine/browser/frame_impl.cc

@@ -493,6 +493,14 @@ void FrameImpl::OnMediaPlayerDisconnect() {
   media_player_ = nullptr;
 }
 
+void FrameImpl::OnAccessibilityError(zx_status_t error) {
+  // The task is posted so |accessibility_bridge_| does not tear |this| down
+  // while events are still being processed.
+  base::ThreadTaskRunnerHandle::Get()->PostTask(
+      FROM_HERE, base::BindOnce(&FrameImpl::CloseAndDestroyFrame,
+                                weak_factory_.GetWeakPtr(), error));
+}
+
 bool FrameImpl::MaybeHandleCastStreamingMessage(
     std::string* origin,
     fuchsia::web::WebMessage* message,
@@ -572,7 +580,7 @@ void FrameImpl::CreateViewWithViewRef(
       semantics_manager_for_test_ ? semantics_manager_for_test_
                                   : semantics_manager.get(),
       window_tree_host_->CreateViewRef(), web_contents_.get(),
-      base::BindOnce(&FrameImpl::CloseAndDestroyFrame, base::Unretained(this)));
+      base::BindOnce(&FrameImpl::OnAccessibilityError, base::Unretained(this)));
 }
 
 void FrameImpl::GetMediaPlayer(
@@ -775,7 +783,7 @@ void FrameImpl::EnableHeadlessRendering() {
     accessibility_bridge_ = std::make_unique<AccessibilityBridge>(
         semantics_manager_for_test_, window_tree_host_->CreateViewRef(),
         web_contents_.get(),
-        base::BindOnce(&FrameImpl::CloseAndDestroyFrame,
+        base::BindOnce(&FrameImpl::OnAccessibilityError,
                        base::Unretained(this)));
 
     // Set bounds for testing hit testing.

fuchsia/engine/browser/frame_impl.h

@@ -119,6 +119,9 @@ class FrameImpl : public fuchsia::web::Frame,
   // Cleans up the MediaPlayerImpl on disconnect.
   void OnMediaPlayerDisconnect();
 
+  // An error handler for |accessibility_bridge_|.
+  void OnAccessibilityError(zx_status_t error);
+
   // Initializes WindowTreeHost for the view with the specified |view_token|.
   // |view_token| may be uninitialized in headless mode.
   void InitWindowTreeHost(fuchsia::ui::views::ViewToken view_token,
@@ -288,6 +291,8 @@ class FrameImpl : public fuchsia::web::Frame,
   media_control::MediaBlocker media_blocker_;
 
   ThemeManager theme_manager_;
+
+  base::WeakPtrFactory<FrameImpl> weak_factory_{this};
 };
 
 #endif  // FUCHSIA_ENGINE_BROWSER_FRAME_IMPL_H_