Avoid hide backdrop for homecher

Bug: 877163
Change-Id: I9f1b221bbbfbfb34d4a796c109ef7595e17bbc40
Reviewed-on: https://chromium-review.googlesource.com/1195928
Commit-Queue: Weidong Guo <weidongg@chromium.org>
Reviewed-by: Xiyuan Xia <xiyuan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#587636}

ash/app_list/app_list_presenter_delegate_unittest.cc

@@ -24,6 +24,7 @@
 #include "ash/shelf/shelf_layout_manager.h"
 #include "ash/shelf/shelf_view.h"
 #include "ash/shell.h"
+#include "ash/shell_test_api.h"
 #include "ash/test/ash_test_base.h"
 #include "ash/wallpaper/wallpaper_controller_test_api.h"
 #include "ash/wm/overview/window_selector_controller.h"
@@ -32,6 +33,7 @@
 #include "ash/wm/tablet_mode/tablet_mode_controller.h"
 #include "ash/wm/window_state.h"
 #include "ash/wm/window_util.h"
+#include "ash/wm/workspace_controller_test_api.h"
 #include "base/command_line.h"
 #include "base/macros.h"
 #include "base/run_loop.h"
@@ -1607,4 +1609,19 @@ TEST_F(AppListPresenterDelegateHomeLauncherTest,
   GetAppListTestHelper()->CheckVisibility(true);
 }
 
+// Test backdrop exists for active non-fullscreen window in tablet mode.
+TEST_F(AppListPresenterDelegateHomeLauncherTest, BackdropTest) {
+  WorkspaceControllerTestApi test_helper(
+      ShellTestApi(Shell::Get()).workspace_controller());
+  EnableTabletMode(true);
+  GetAppListTestHelper()->CheckVisibility(true);
+  EXPECT_FALSE(test_helper.GetBackdropWindow());
+
+  std::unique_ptr<aura::Window> non_fullscreen_window(
+      CreateTestWindow(gfx::Rect(0, 0, 100, 100)));
+  non_fullscreen_window->Show();
+  GetAppListTestHelper()->CheckVisibility(true);
+  EXPECT_TRUE(test_helper.GetBackdropWindow());
+}
+
 }  // namespace ash

ash/wm/workspace/backdrop_controller.cc

@@ -126,8 +126,11 @@ void BackdropController::UpdateBackdrop() {
 
   AppListControllerImpl* app_list_controller =
       Shell::Get()->app_list_controller();
-  // Only hide the backdrop of the display that launcher is opened at.
-  if (app_list_controller && app_list_controller->GetTargetVisibility() &&
+  // Hide the backdrop when it is in the same display of launcher and
+  // launcher is not in home launcher mode.
+  if (app_list_controller &&
+      !app_list_controller->IsHomeLauncherEnabledInTabletMode() &&
+      app_list_controller->GetTargetVisibility() &&
       app_list_controller->presenter()->GetView() &&
       container_->GetRootWindow() == app_list_controller->presenter()
                                          ->GetView()