assistant: update assistant location when display metrics change

Bug: b/111900963, b/112102455
Test: Manual
Change-Id: I69f296f8eae6eb320eb5be122629b8e1658868ce
Reviewed-on: https://chromium-review.googlesource.com/1173478
Commit-Queue: Muyuan Li <muyuanli@chromium.org>
Reviewed-by: Xiaohui Chen <xiaohuic@chromium.org>
Cr-Commit-Position: refs/heads/master@{#582786}

ash/assistant/ui/assistant_container_view.cc

@@ -115,8 +115,7 @@ AssistantContainerView::AssistantContainerView(
     AssistantController* assistant_controller)
     : assistant_controller_(assistant_controller) {
   set_accept_events(true);
-  SetAnchor();
-  set_arrow(views::BubbleBorder::Arrow::BOTTOM_CENTER);
+  SetAnchor(nullptr);
   set_close_on_deactivate(false);
   set_color(kBackgroundColor);
   set_margins(gfx::Insets());
@@ -131,9 +130,11 @@ AssistantContainerView::AssistantContainerView(
   // The AssistantController owns the view hierarchy to which
   // AssistantContainerView belongs so is guaranteed to outlive it.
   assistant_controller_->ui_controller()->AddModelObserver(this);
+  display::Screen::GetScreen()->AddObserver(this);
 }
 
 AssistantContainerView::~AssistantContainerView() {
+  display::Screen::GetScreen()->RemoveObserver(this);
   assistant_controller_->ui_controller()->RemoveModelObserver(this);
 }
 
@@ -237,11 +238,12 @@ void AssistantContainerView::RequestFocus() {
   }
 }
 
-// TODO(dmblack): Handle dynamic re-anchoring due to shelf repositioning, etc.
-void AssistantContainerView::SetAnchor() {
+void AssistantContainerView::SetAnchor(aura::Window* root_window) {
+  if (!root_window)
+    root_window = Shell::Get()->GetRootWindowForNewWindows();
   // Anchor to the display matching where new windows will be opened.
   display::Display display = display::Screen::GetScreen()->GetDisplayMatching(
-      Shell::Get()->GetRootWindowForNewWindows()->GetBoundsInScreen());
+      root_window->GetBoundsInScreen());
 
   // Anchor to the bottom center of the work area.
   gfx::Rect work_area = display.work_area();
@@ -249,6 +251,7 @@ void AssistantContainerView::SetAnchor() {
                                work_area.width(), 0);
 
   SetAnchorRect(anchor);
+  set_arrow(views::BubbleBorder::Arrow::BOTTOM_CENTER);
 }
 
 void AssistantContainerView::OnUiModeChanged(AssistantUiMode ui_mode) {
@@ -301,4 +304,12 @@ void AssistantContainerView::AnimationProgressed(
   GetWidget()->SetBounds(bounds);
 }
 
+void AssistantContainerView::OnDisplayMetricsChanged(
+    const display::Display& display,
+    uint32_t changed_metrics) {
+  aura::Window* root_window = GetWidget()->GetNativeWindow()->GetRootWindow();
+  if (root_window == Shell::Get()->GetRootWindowForDisplayId(display.id()))
+    SetAnchor(root_window);
+}
+
 }  // namespace ash

ash/assistant/ui/assistant_container_view.h

@@ -7,6 +7,7 @@
 
 #include "ash/assistant/model/assistant_ui_model_observer.h"
 #include "base/macros.h"
+#include "ui/display/display_observer.h"
 #include "ui/gfx/animation/animation_delegate.h"
 #include "ui/views/bubble/bubble_dialog_delegate_view.h"
 
@@ -14,6 +15,10 @@ namespace gfx {
 class SlideAnimation;
 }  // namespace gfx
 
+namespace aura {
+class Window;
+}  // namespace aura
+
 namespace ash {
 
 class AssistantController;
@@ -23,6 +28,7 @@ class AssistantWebView;
 
 class AssistantContainerView : public views::BubbleDialogDelegateView,
                                public AssistantUiModelObserver,
+                               public display::DisplayObserver,
                                public gfx::AnimationDelegate {
  public:
   explicit AssistantContainerView(AssistantController* assistant_controller);
@@ -44,8 +50,18 @@ class AssistantContainerView : public views::BubbleDialogDelegateView,
   // gfx::AnimationDelegate:
   void AnimationProgressed(const gfx::Animation* animation) override;
 
+  // display::DisplayObserver:
+  void OnWillProcessDisplayChanges() override {}
+  void OnDidProcessDisplayChanges() override {}
+  void OnDisplayAdded(const display::Display& new_display) override {}
+  void OnDisplayRemoved(const display::Display& old_display) override {}
+  void OnDisplayMetricsChanged(const display::Display& display,
+                               uint32_t changed_metrics) override;
+
  private:
-  void SetAnchor();
+  // Sets anchor rect to |root_window|. If it's null,
+  // result of GetRootWindowForNewWindows() will be used.
+  void SetAnchor(aura::Window* root_window);
 
   AssistantController* const assistant_controller_;  // Owned by Shell.