Update voice interaction animation timing

Add overall animation start startup delay after inital touch. Remove
the icon background visibility delay to work with the new overall
delay.

BUG=b:35624617
TEST=build and flash locally, saw the animation changes

Review-Url: https://codereview.chromium.org/2953283003
Cr-Commit-Position: refs/heads/master@{#483045}

diff --git a/ash/shelf/app_list_button.h b/ash/shelf/app_list_button.h
index 987fe19..6ad53960 100644
--- a/ash/shelf/app_list_button.h
+++ b/ash/shelf/app_list_button.h

@@ -13,6 +13,10 @@
 #include "third_party/skia/include/core/SkColor.h"
 #include "ui/views/controls/button/image_button.h"
 
+namespace base {
+class OneShotTimer;
+}  // namespace base
+
 namespace ash {
 class InkDropButtonListener;
 class Shelf;
@@ -75,6 +79,7 @@
   Shelf* shelf_;
 
   VoiceInteractionOverlay* voice_interaction_overlay_;
+  std::unique_ptr<base::OneShotTimer> voice_interaction_animation_delay_timer_;
 
   bool voice_interaction_running_ = false;