Adds tooltips for new Accessibility trays: Select-to-Speak and Dictation.

Change-Id: Ia95b34635305bd2e0d7d4ce4c006fc8e9fd65aae
Reviewed-on: https://chromium-review.googlesource.com/1091500Reviewed-by: Steven Bennetts <stevenjb@chromium.org>
Commit-Queue: Katie Dektar <katie@chromium.org>
Cr-Commit-Position: refs/heads/master@{#565405}

ash/system/accessibility/dictation_button_tray.cc

@@ -31,6 +31,8 @@ DictationButtonTray::DictationButtonTray(Shelf* shelf)
   const int horizontal_padding = (kTrayItemSize - off_image_.width()) / 2;
   icon_->SetBorder(views::CreateEmptyBorder(
       gfx::Insets(vertical_padding, horizontal_padding)));
+  icon_->SetTooltipText(
+      l10n_util::GetStringUTF16(IDS_ASH_STATUS_TRAY_ACCESSIBILITY_DICTATION));
   tray_container()->AddChildView(icon_);
   Shell::Get()->AddShellObserver(this);
   Shell::Get()->accessibility_controller()->AddObserver(this);

ash/system/accessibility/select_to_speak_tray.cc

@@ -41,6 +41,8 @@ SelectToSpeakTray::SelectToSpeakTray(Shelf* shelf)
   const int horizontal_padding = (kTrayItemSize - inactive_image_.width()) / 2;
   icon_->SetBorder(views::CreateEmptyBorder(
       gfx::Insets(vertical_padding, horizontal_padding)));
+  icon_->SetTooltipText(l10n_util::GetStringUTF16(
+      IDS_ASH_STATUS_TRAY_ACCESSIBILITY_SELECT_TO_SPEAK));
   tray_container()->AddChildView(icon_);
   CheckStatusAndUpdateIcon();