ws: Add a DesktopWindowTreeHostMus test for setting bounds during init

Adds a unit test split out from https://crrev.com/c/1311080 (PS9)
Landing separately to make release branch merging easier.

Bug: 899084
Test: Automated
Change-Id: Icadd82f2490bc4f3bbbdd1c73f8cdbe584f03289
Reviewed-on: https://chromium-review.googlesource.com/c/1318363
Commit-Queue: Michael Wasserman <msw@chromium.org>
Reviewed-by: Scott Violet <sky@chromium.org>
Cr-Commit-Position: refs/heads/master@{#605623}

ui/aura/test/mus/test_window_tree.cc

@@ -169,6 +169,7 @@ void TestWindowTree::SetWindowBounds(
     const base::Optional<viz::LocalSurfaceId>& local_surface_id) {
   window_id_ = window_id;
   last_local_surface_id_ = local_surface_id;
+  second_last_set_window_bounds_ = last_set_window_bounds_;
   last_set_window_bounds_ = bounds;
   OnChangeReceived(change_id, WindowTreeChangeType::BOUNDS);
 }

ui/aura/test/mus/test_window_tree.h

@@ -120,6 +120,9 @@ class TestWindowTree : public ws::mojom::WindowTree {
   const gfx::Rect& last_set_window_bounds() const {
     return last_set_window_bounds_;
   }
+  const gfx::Rect& second_last_set_window_bounds() const {
+    return second_last_set_window_bounds_;
+  }
 
   ws::Id last_not_cancelled_window_id() const {
     return last_not_cancelled_window_id_;
@@ -295,7 +298,11 @@ class TestWindowTree : public ws::mojom::WindowTree {
 
   base::Optional<viz::LocalSurfaceId> last_local_surface_id_;
 
+  // Records the last *two* window bounds set, useful for top-level windows,
+  // where each client-side DesktopWindowTreeHostMus has two aura::Windows (for
+  // the frame and the content), and both set bounds during views::Widget::Init.
   gfx::Rect last_set_window_bounds_;
+  gfx::Rect second_last_set_window_bounds_;
 
   ws::Id last_not_cancelled_window_id_ = 0u;
   ws::Id last_cancelled_window_id_ = 0u;

ui/views/mus/desktop_window_tree_host_mus_unittest.cc

@@ -4,6 +4,7 @@
 
 #include "ui/views/mus/desktop_window_tree_host_mus.h"
 
+#include "base/command_line.h"
 #include "base/strings/utf_string_conversions.h"
 #include "base/test/bind_test_util.h"
 #include "services/ws/test_ws/test_ws.mojom.h"
@@ -22,10 +23,12 @@
 #include "ui/aura/test/mus/test_window_tree.h"
 #include "ui/aura/test/mus/window_tree_client_test_api.h"
 #include "ui/aura/window.h"
+#include "ui/display/display_switches.h"
 #include "ui/events/base_event_utils.h"
 #include "ui/events/event.h"
 #include "ui/events/gestures/gesture_recognizer.h"
 #include "ui/events/gestures/gesture_recognizer_observer.h"
+#include "ui/gfx/geometry/dip_util.h"
 #include "ui/views/accessibility/view_accessibility.h"
 #include "ui/views/mus/mus_client.h"
 #include "ui/views/mus/mus_client_test_api.h"
@@ -412,6 +415,50 @@ TEST_F(DesktopWindowTreeHostMusTest, CreateFullscreenWidget) {
   }
 }
 
+// DesktopWindowTreeHostMusTest with --force-device-scale-factor=2.
+class DesktopWindowTreeHostMusTestHighDPI
+    : public DesktopWindowTreeHostMusTest {
+ public:
+  DesktopWindowTreeHostMusTestHighDPI() = default;
+  ~DesktopWindowTreeHostMusTestHighDPI() override = default;
+
+  // DesktopWindowTreeHostMusTest:
+  void SetUp() override {
+    base::CommandLine::ForCurrentProcess()->AppendSwitchASCII(
+        switches::kForceDeviceScaleFactor, "2");
+    DesktopWindowTreeHostMusTest::SetUp();
+  }
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(DesktopWindowTreeHostMusTestHighDPI);
+};
+
+// Ensure menu widgets correctly scale initial bounds: http://crbug.com/899084
+TEST_F(DesktopWindowTreeHostMusTestHighDPI, InitializeMenuWithDIPBounds) {
+  // Swap the WindowTree implementation to verify SetWindowBounds() is called
+  // with the correct DIP bounds, using the host's cached device_scale_factor.
+  aura::TestWindowTree test_window_tree;
+  aura::WindowTreeClientTestApi test_api(
+      MusClient::Get()->window_tree_client());
+  ws::mojom::WindowTree* old_tree = test_api.SwapTree(&test_window_tree);
+
+  Widget widget;
+  Widget::InitParams params(Widget::InitParams::TYPE_MENU);
+  params.ownership = Widget::InitParams::WIDGET_OWNS_NATIVE_WIDGET;
+  params.bounds = gfx::Rect(2, 4, 60, 80);
+  widget.Init(params);
+
+  // Check the second-last set window bounds (for the frame, not the content).
+  EXPECT_EQ(params.bounds, test_window_tree.second_last_set_window_bounds());
+  EXPECT_EQ(params.bounds, widget.GetWindowBoundsInScreen());
+  EXPECT_EQ(2.0f, widget.GetNativeWindow()->GetHost()->device_scale_factor());
+  gfx::Rect pixels(gfx::ConvertRectToPixel(2.0f, params.bounds));
+  EXPECT_EQ(pixels, widget.GetNativeWindow()->GetHost()->GetBoundsInPixels());
+
+  widget.CloseNow();
+  test_api.SwapTree(old_tree);
+}
+
 TEST_F(DesktopWindowTreeHostMusTest, GetWindowBoundsInScreen) {
   ScreenMus* screen = MusClientTestApi::screen();