back_gesture: Enable left swipe to exit home screen search result page.

Bug: 1002733
Change-Id: I79cff30c75781b5bb99aaf6d9d9a613506a23e8c
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1872446Reviewed-by: Xiyuan Xia <xiyuan@chromium.org>
Commit-Queue: Min Chen <minch@chromium.org>
Cr-Commit-Position: refs/heads/master@{#708219}

ash/wm/toplevel_window_event_handler.cc

@@ -4,7 +4,9 @@
 
 #include "ash/wm/toplevel_window_event_handler.h"
 
+#include "ash/app_list/app_list_controller_impl.h"
 #include "ash/home_screen/home_screen_controller.h"
+#include "ash/public/cpp/app_list/app_list_types.h"
 #include "ash/public/cpp/app_types.h"
 #include "ash/public/cpp/ash_features.h"
 #include "ash/session/session_controller_impl.h"
@@ -128,9 +130,13 @@ bool CanStartGoingBack(aura::Window* target) {
     return false;
   }
 
-  // Do not enable back gesture if home screen is visible.
-  if (shell->home_screen_controller()->IsHomeScreenVisible())
+  // Do not enable back gesture if home screen is visible but not in
+  // |kFullscreenSearch| state.
+  if (shell->home_screen_controller()->IsHomeScreenVisible() &&
+      shell->app_list_controller()->GetAppListViewState() !=
+          AppListViewState::kFullscreenSearch) {
     return false;
+  }
 
   views::Widget* widget = views::Widget::GetTopLevelWidgetForNativeView(target);
   if (!widget)

ash/wm/toplevel_window_event_handler_unittest.cc

@@ -5,6 +5,9 @@
 #include "ash/wm/toplevel_window_event_handler.h"
 
 #include "ash/accelerators/accelerator_controller_impl.h"
+#include "ash/app_list/test/app_list_test_helper.h"
+#include "ash/app_list/views/app_list_view.h"
+#include "ash/app_list/views/search_box_view.h"
 #include "ash/display/screen_orientation_controller.h"
 #include "ash/display/screen_orientation_controller_test_api.h"
 #include "ash/home_screen/home_screen_controller.h"
@@ -1162,11 +1165,13 @@ TEST_F(ToplevelWindowEventHandlerBackGestureTest, DonotStartGoingBack) {
   EXPECT_EQ(0, target_back_press.accelerator_count());
   EXPECT_EQ(0, target_back_release.accelerator_count());
 
-  // Should not go back if home screen is not visible.
+  // Should not go back if home screen is visible and in |kFullscreenAllApps|
+  // state.
   shell->overview_controller()->EndOverview();
   ASSERT_FALSE(shell->overview_controller()->InOverviewSession());
   shell->home_screen_controller()->GoHome(GetPrimaryDisplay().id());
   ASSERT_TRUE(shell->home_screen_controller()->IsHomeScreenVisible());
+  GetAppListTestHelper()->CheckState(AppListViewState::kFullscreenAllApps);
   generator->GestureScrollSequence(
       start,
       gfx::Point(ToplevelWindowEventHandler::kSwipingDistanceForGoingBack + 10,
@@ -1174,6 +1179,22 @@ TEST_F(ToplevelWindowEventHandlerBackGestureTest, DonotStartGoingBack) {
       base::TimeDelta::FromMilliseconds(100), 3);
   EXPECT_EQ(0, target_back_press.accelerator_count());
   EXPECT_EQ(0, target_back_release.accelerator_count());
+
+  // Should exit |kFullscreenSearch| to enter |kFullscreenAllApps| state while
+  // home screen search result page is opened.
+  generator->GestureTapAt(GetAppListTestHelper()
+                              ->GetAppListView()
+                              ->search_box_view()
+                              ->GetBoundsInScreen()
+                              .CenterPoint());
+  GetAppListTestHelper()->CheckState(AppListViewState::kFullscreenSearch);
+  generator->GestureScrollSequence(
+      start,
+      gfx::Point(ToplevelWindowEventHandler::kSwipingDistanceForGoingBack + 10,
+                 100),
+      base::TimeDelta::FromMilliseconds(100), 3);
+  EXPECT_EQ(1, target_back_release.accelerator_count());
+  GetAppListTestHelper()->CheckState(AppListViewState::kFullscreenAllApps);
 }
 
 namespace {