Add extension dialog title to accessible node data

Screen readers should read the title ("Add <extension>?") of extension
install dialogs.

Bug: 849910
Change-Id: I9d37b3810c046419f4c5a3b4428a57cb0a5f3289
Reviewed-on: https://chromium-review.googlesource.com/1135595
Commit-Queue: James Wallace-Lee <jamwalla@chromium.org>
Reviewed-by: Devlin <rdevlin.cronin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#578713}

chrome/browser/ui/views/extensions/extension_install_dialog_view.cc

@@ -240,6 +240,7 @@ ExtensionInstallDialogView::ExtensionInstallDialogView(
       navigator_(navigator),
       done_callback_(done_callback),
       prompt_(std::move(prompt)),
+      title_(prompt_->GetDialogTitle()),
       scroll_view_(nullptr),
       handled_result_(false),
       install_button_enabled_(false) {
@@ -471,8 +472,7 @@ void ExtensionInstallDialogView::AddedToWidget() {
   layout->AddView(icon);
 
   std::unique_ptr<views::Label> title_label =
-      views::BubbleFrameView::CreateDefaultTitleLabel(
-          prompt_->GetDialogTitle());
+      views::BubbleFrameView::CreateDefaultTitleLabel(title_);
   // Setting the title's preferred size to 0 ensures it won't influence the
   // overall size of the dialog. It will be expanded by GridLayout.
   title_label->SetPreferredSize(gfx::Size(0, 0));
@@ -547,6 +547,14 @@ void ExtensionInstallDialogView::UpdateInstallResultHistogram(bool accepted)
     UMA_HISTOGRAM_BOOLEAN("Extensions.InstallPrompt.Accepted", accepted);
 }
 
+ax::mojom::Role ExtensionInstallDialogView::GetAccessibleWindowRole() const {
+  return ax::mojom::Role::kAlertDialog;
+}
+
+base::string16 ExtensionInstallDialogView::GetAccessibleWindowTitle() const {
+  return title_;
+}
+
 // ExpandableContainerView::DetailsView ----------------------------------------
 
 ExpandableContainerView::DetailsView::DetailsView(

chrome/browser/ui/views/extensions/extension_install_dialog_view.h

@@ -60,6 +60,8 @@ class ExtensionInstallDialogView : public views::DialogDelegateView,
   ui::ModalType GetModalType() const override;
   views::View* CreateExtraView() override;
   bool IsDialogButtonEnabled(ui::DialogButton button) const override;
+  ax::mojom::Role GetAccessibleWindowRole() const override;
+  base::string16 GetAccessibleWindowTitle() const override;
 
   // views::LinkListener:
   void LinkClicked(views::Link* source, int event_flags) override;
@@ -82,6 +84,7 @@ class ExtensionInstallDialogView : public views::DialogDelegateView,
   content::PageNavigator* navigator_;
   ExtensionInstallPrompt::DoneCallback done_callback_;
   std::unique_ptr<ExtensionInstallPrompt::Prompt> prompt_;
+  base::string16 title_;
 
   // The scroll view containing all the details for the dialog (including all
   // collapsible/expandable sections).