Blends Shelf into Launcher to help fix FPS on low-end devices

Bug: 883032
Change-Id: Ib65bc5fb61f0526d9ccc688769f1f68284f3bfeb
Reviewed-on: https://chromium-review.googlesource.com/c/1269860
Commit-Queue: Kevin Strohbehn <ginko@google.com>
Reviewed-by: Xiyuan Xia <xiyuan@chromium.org>
Reviewed-by: Weidong Guo <weidongg@chromium.org>
Reviewed-by: Alex Newcomer <newcomer@chromium.org>
Cr-Commit-Position: refs/heads/master@{#600151}

ash/app_list/views/app_list_view.cc

@@ -575,8 +575,8 @@ void AppListView::InitContents(int initial_apps_page) {
   SetBackgroundShieldColor();
   if (is_background_blur_enabled_ && !IsHomeLauncherEnabledInTabletMode()) {
     app_list_background_shield_mask_ = views::Painter::CreatePaintedLayer(
-        views::Painter::CreateSolidRoundRectPainter(
-            SK_ColorBLACK, AppListConfig::instance().blur_radius()));
+        views::Painter::CreateSolidRoundRectPainter(SK_ColorBLACK,
+                                                    kAppListBackgroundRadius));
     app_list_background_shield_mask_->layer()->SetFillsBoundsOpaquely(false);
     app_list_background_shield_->layer()->SetMaskLayer(
         app_list_background_shield_mask_->layer());

ash/shelf/shelf_layout_manager.cc

@@ -97,10 +97,8 @@ bool IsTabletModeEnabled() {
 
 // TODO(sammiequon): This should be the same as IsTabletModeEnabled once home
 // launcher flag is removed.
-bool IsHomeLauncherEnabled() {
-  return Shell::Get()
-      ->app_list_controller()
-      ->IsHomeLauncherEnabledInTabletMode();
+bool IsHomeLauncherEnabledInTabletMode() {
+  return app_list_features::IsHomeLauncherEnabled() && IsTabletModeEnabled();
 }
 
 }  // namespace
@@ -549,7 +547,7 @@ ShelfBackgroundType ShelfLayoutManager::GetShelfBackgroundType() const {
 
   // If the app list is active and the home launcher is not shown, hide the
   // shelf background to prevent overlap.
-  if (is_app_list_visible_ && !IsHomeLauncherEnabled())
+  if (is_app_list_visible_ && !IsHomeLauncherEnabledInTabletMode())
     return SHELF_BACKGROUND_APP_LIST;
 
   if (state_.visibility_state != SHELF_AUTO_HIDE &&
@@ -1001,7 +999,7 @@ ShelfAutoHideState ShelfLayoutManager::CalculateAutoHideState(
   if (visibility_state != SHELF_AUTO_HIDE)
     return SHELF_AUTO_HIDE_HIDDEN;
 
-  if (shelf_widget_->IsShowingAppList() && !IsHomeLauncherEnabled())
+  if (shelf_widget_->IsShowingAppList() && !IsHomeLauncherEnabledInTabletMode())
     return SHELF_AUTO_HIDE_SHOWN;
 
   if (shelf_widget_->status_area_widget() &&
@@ -1221,7 +1219,7 @@ void ShelfLayoutManager::StartGestureDrag(
     }
 
     // Disable the shelf dragging if the fullscreen app list is opened.
-    if (is_app_list_visible_ && !IsHomeLauncherEnabled())
+    if (is_app_list_visible_ && !IsHomeLauncherEnabledInTabletMode())
       return;
 
     gesture_drag_status_ = GESTURE_DRAG_IN_PROGRESS;
@@ -1391,7 +1389,7 @@ bool ShelfLayoutManager::CanStartFullscreenAppListDrag(
   // In overview mode, app list for tablet mode is hidden temporarily and will
   // be shown automatically after overview mode ends. So prevent opening it
   // here.
-  if (IsHomeLauncherEnabled())
+  if (IsHomeLauncherEnabledInTabletMode())
     return false;
 
   return true;

ash/shelf/shelf_widget.cc

@@ -189,7 +189,9 @@ void ShelfWidget::DelegateView::ReorderChildLayers(ui::Layer* parent_layer) {
 }
 
 void ShelfWidget::DelegateView::UpdateBackgroundBlur() {
+  // Blur only if the background is visible.
   const bool should_blur_background =
+      opaque_background_.visible() &&
       shelf_widget_->shelf_layout_manager()->ShouldBlurShelfBackground();
   if (should_blur_background == background_is_currently_blurred_)
     return;
@@ -208,6 +210,19 @@ void ShelfWidget::DelegateView::UpdateOpaqueBackground() {
   const ShelfBackgroundType background_type =
       shelf_widget_->GetBackgroundType();
 
+  // If the app list is showing in clamshell mode, we should hide the shelf.
+  // otherwise, we should show it again. This creates a 'blending' effect
+  // between the two
+  if (background_type == SHELF_BACKGROUND_APP_LIST) {
+    opaque_background_.SetVisible(false);
+    UpdateBackgroundBlur();
+    return;
+  }
+
+  if (!opaque_background_.visible()) {
+    opaque_background_.SetVisible(true);
+  }
+
   // Show rounded corners except in maximized and split modes.
   if (background_type == SHELF_BACKGROUND_MAXIMIZED ||
       background_type == SHELF_BACKGROUND_SPLIT_VIEW) {