Revert "[reland] In tablet mode, tap on overview background should go to home screen."

This reverts commit 82f9896f.

Reason for revert: 
OverviewSessionWithDragFromShelfFeatureTest.TapOnBackgroundGoToHome is failing on linux-chromeos-rel
https://ci.chromium.org/p/chromium/builders/ci/linux-chromeos-rel

Original change's description:
> [reland] In tablet mode, tap on overview background should go to home screen.
> 
> Clamshell mode behavior will remain the same, i.e., tapping on the
> overview background will return to its previous state, it can either be
> in-app or home screen.
> 
> Bug: 997885
> 
> Change-Id: I2dae82657d4d92876c834c78dd62d53830fbe6cf
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1865264
> Commit-Queue: Xiaoqian Dai <xdai@chromium.org>
> Reviewed-by: Xiaoqian Dai <xdai@chromium.org>
> Reviewed-by: Xiyuan Xia <xiyuan@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#707036}

TBR=xiyuan@chromium.org,xdai@chromium.org

Change-Id: I5dd88e82ecb8d5c3772be87fb749c3da88ba6d08
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: 997885
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1867472Reviewed-by: Lan Wei <lanwei@chromium.org>
Commit-Queue: Lan Wei <lanwei@chromium.org>
Cr-Commit-Position: refs/heads/master@{#707132}

ash/wm/overview/overview_grid_event_handler.cc

@@ -4,8 +4,6 @@
 
 #include "ash/wm/overview/overview_grid_event_handler.h"
 
-#include "ash/home_screen/home_screen_controller.h"
-#include "ash/public/cpp/ash_features.h"
 #include "ash/root_window_controller.h"
 #include "ash/shell.h"
 #include "ash/wallpaper/wallpaper_view.h"
@@ -14,7 +12,6 @@
 #include "ash/wm/overview/overview_grid.h"
 #include "ash/wm/overview/overview_utils.h"
 #include "ui/compositor/compositor.h"
-#include "ui/display/screen.h"
 #include "ui/events/event.h"
 #include "ui/events/gestures/fling_curve.h"
 
@@ -131,20 +128,8 @@ void OverviewGridEventHandler::HandleClickOrTap(ui::Event* event) {
   CHECK_EQ(ui::EP_PRETARGET, event->phase());
   // Events that happen while app list is sliding out during overview should
   // be ignored to prevent overview from disappearing out from under the user.
-  if (!IsSlidingOutOverviewFromShelf()) {
-    if (Shell::Get()->tablet_mode_controller()->InTabletMode() &&
-        features::IsDragFromShelfToHomeOrOverviewEnabled()) {
-      // In tablet mode, clicking on tapping on the wallpaper background will
-      // always head back to home launcher screen.
-      int64_t display_id = display::Screen::GetScreen()
-                               ->GetDisplayNearestWindow(
-                                   static_cast<aura::Window*>(event->target()))
-                               .id();
-      Shell::Get()->home_screen_controller()->GoHome(display_id);
-    } else {
-      Shell::Get()->overview_controller()->EndOverview();
-    }
-  }
+  if (!IsSlidingOutOverviewFromShelf())
+    Shell::Get()->overview_controller()->EndOverview();
   event->StopPropagation();
 }
 

ash/wm/overview/overview_session_unittest.cc

@@ -17,13 +17,11 @@
 #include "ash/display/screen_orientation_controller.h"
 #include "ash/display/screen_orientation_controller_test_api.h"
 #include "ash/drag_drop/drag_drop_controller.h"
-#include "ash/home_screen/home_screen_controller.h"
 #include "ash/magnifier/docked_magnifier_controller_impl.h"
 #include "ash/public/cpp/app_types.h"
 #include "ash/public/cpp/ash_features.h"
 #include "ash/public/cpp/fps_counter.h"
 #include "ash/public/cpp/shelf_config.h"
-#include "ash/public/cpp/test/shell_test_api.h"
 #include "ash/public/cpp/window_properties.h"
 #include "ash/screen_util.h"
 #include "ash/shelf/shelf.h"
@@ -2792,50 +2790,6 @@ TEST_P(OverviewSessionTest, ShelfAlignmentChangeWhileInOverview) {
   EXPECT_FALSE(InOverviewSession());
 }
 
-// The class to test overview behavior with kDragFromShelfToHomeOrOverview flag
-// enabled.
-class OverviewSessionWithDragFromShelfFeatureTest : public OverviewSessionTest {
- public:
-  OverviewSessionWithDragFromShelfFeatureTest() = default;
-  ~OverviewSessionWithDragFromShelfFeatureTest() override = default;
-
-  void SetUp() override {
-    scoped_feature_list_.InitAndEnableFeature(
-        features::kDragFromShelfToHomeOrOverview);
-    OverviewSessionTest::SetUp();
-    EnterTabletMode();
-  }
-
- private:
-  base::test::ScopedFeatureList scoped_feature_list_;
-
-  DISALLOW_COPY_AND_ASSIGN(OverviewSessionWithDragFromShelfFeatureTest);
-};
-
-// Tests that in tablet mode, tapping on the background will always go to home
-// screen.
-TEST_P(OverviewSessionWithDragFromShelfFeatureTest, TapOnBackgroundGoToHome) {
-  UpdateDisplay("800x600");
-  std::unique_ptr<aura::Window> window(CreateTestWindow());
-  WindowState* window_state = WindowState::Get(window.get());
-
-  EXPECT_FALSE(window_state->IsMinimized());
-  EXPECT_FALSE(Shell::Get()->home_screen_controller()->IsHomeScreenVisible());
-  ToggleOverview();
-  EXPECT_TRUE(InOverviewSession());
-
-  // Tap on the background.
-  ui::ScopedAnimationDurationScaleMode test_duration_mode(
-      ui::ScopedAnimationDurationScaleMode::NON_ZERO_DURATION);
-  GetEventGenerator()->GestureTapAt(gfx::Point(10, 10));
-  ShellTestApi().WaitForOverviewAnimationState(
-      OverviewAnimationState::kExitAnimationComplete);
-
-  EXPECT_FALSE(InOverviewSession());
-  EXPECT_TRUE(window_state->IsMinimized());
-  EXPECT_TRUE(Shell::Get()->home_screen_controller()->IsHomeScreenVisible());
-}
-
 // TODO(sammiequon): Merge this into SplitViewOverviewSessionTest and rename
 // that to TabletModeOverviewSessionTest.
 class OverviewSessionNewLayoutTest : public OverviewSessionTest {
@@ -5297,8 +5251,5 @@ INSTANTIATE_TEST_SUITE_P(
     ,
     SplitViewOverviewSessionInClamshellTestMultiDisplayOnly,
     testing::Values(true));
-INSTANTIATE_TEST_SUITE_P(,
-                         OverviewSessionWithDragFromShelfFeatureTest,
-                         testing::Bool());
 
 }  // namespace ash