AdjustBoundsToEnsureMinimumWindowVisibility may cause unwanted shift if window dimension is small

ash/wm/window_state_unittest.cc

Index: ash/wm/window_state_unittest.cc
diff --git a/ash/wm/window_state_unittest.cc b/ash/wm/window_state_unittest.cc
index 1a1bf33c1d494ffb4968e091beabfef8aeb84649..d2860f609950449f49f3cefb1a482d35cf985ea9 100644
--- a/ash/wm/window_state_unittest.cc
+++ b/ash/wm/window_state_unittest.cc
@@ -7,6 +7,7 @@
 #include <utility>
 
 #include "ash/common/material_design/material_design_controller.h"
+#include "ash/common/shelf/wm_shelf.h"
 #include "ash/common/wm/window_state.h"
 #include "ash/common/wm/wm_event.h"
 #include "ash/screen_util.h"
@@ -408,6 +409,29 @@ TEST_P(WindowStateTest, AllowSetBoundsInMaximized) {
   EXPECT_EQ(work_area, window->bounds());
 }
 
+// When there is a workarea bounds changed event caused by shelf layout, the
+// wm::AdjustBoundsToEnsureMinimumWindowVisibility method may cause window
+// bounds change, which leads to the status bubble bug in crbug.com/624806.
+TEST_P(WindowStateTest, AvoidPossibleBoundsChangeIfIgnoredByShelf) {
+  WmShelf* shelf = test::AshTestBase::GetPrimaryShelf();
+  shelf->SetAlignment(ash::SHELF_ALIGNMENT_LEFT);
+  const gfx::Rect display_area =
+      display::Screen::GetScreen()->GetPrimaryDisplay().bounds();
+  std::unique_ptr<aura::Window> window(CreateTestWindowInShellWithId(0));
+  GetWindowState(window.get())->set_ignored_by_shelf(true);
+  // window height should be smaller than wm::kMinimumOnScreenArea,
+  // which is 25 to simulate a status bubble window.
+  gfx::Rect bounds(0, 0, 80, 22);
+  // Ensure the window abuts the bottom of screen.
+  bounds.set_y(display_area.bottom() - bounds.height());
+  window->SetBounds(bounds);
+  EXPECT_EQ(display_area.bottom(), window->bounds().bottom());
+  gfx::Rect expected = window->bounds();
+
+  shelf->SetAlignment(ash::SHELF_ALIGNMENT_BOTTOM);
+  EXPECT_EQ(expected, window->bounds());
+}
+
 // TODO(skuhne): Add more unit test to verify the correctness for the restore
 // operation.