[CrOS PhoneHub] Display PhoneHub bubble view on bottom on a L/R shelf.

Instead of displaying the PhoneHub UI in the middle of the screen
when shelf position is right/left, it is now displayed on the bottom.

Screenshots:
Left shelf - https://screenshot.googleplex.com/5LBcDUSEWY5vER6
Right shelf - https://screenshot.googleplex.com/4AboKZpVjH89tMS
Bottom shelf - https://screenshot.googleplex.com/iumxiW5ohmL9L7w

Fixed: 1159098
Bug: 1106937
Change-Id: Ie715e0f61b46bce469e5aa661e43ac46680d8138
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2600626Reviewed-by: Kyle Horimoto <khorimoto@chromium.org>
Commit-Queue: Regan Hsu <hsuregan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#838947}

ash/system/phonehub/phone_hub_tray.cc

@@ -153,7 +153,9 @@ void PhoneHubTray::ShowBubble(bool show_by_click) {
   TrayBubbleView::InitParams init_params;
   init_params.delegate = this;
   init_params.parent_window = GetBubbleWindowContainer();
-  init_params.anchor_view = GetBubbleAnchor();
+  init_params.anchor_mode = TrayBubbleView::AnchorMode::kRect;
+  init_params.anchor_rect = shelf()->GetSystemTrayAnchorRect();
+  init_params.insets = GetTrayBubbleInsets();
   init_params.shelf_alignment = shelf()->alignment();
   init_params.preferred_width = kTrayMenuWidth;
   init_params.close_on_deactivate = true;
@@ -163,8 +165,6 @@ void PhoneHubTray::ShowBubble(bool show_by_click) {
   init_params.show_by_click = show_by_click;
 
   TrayBubbleView* bubble_view = new TrayBubbleView(init_params);
-  bubble_view->set_anchor_view_insets(GetBubbleAnchorInsets());
-  bubble_view->set_margins(GetSecondaryBubbleInsets());
   bubble_view->SetBorder(views::CreateEmptyBorder(kBubblePadding));
 
   // Creates header view on top for displaying phone status and settings icon.