Ensure menu surface size is not empty

Bug: 1157664
Test: Coverd by unittests
Change-Id: Id2c676779101f10e046ad4b8d168317316fd9db8
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2587610
Commit-Queue: Mitsuru Oshima <oshima@chromium.org>
Reviewed-by: James Cook <jamescook@chromium.org>
Cr-Commit-Position: refs/heads/master@{#836390}

components/exo/wayland/wayland_positioner.cc

@@ -299,7 +299,7 @@ void WaylandPositioner::SetGravity(uint32_t gravity) {
   gravity_y_ = decompose.second;
 }
 
-WaylandPositioner::Result WaylandPositioner::CalculatePosition(
+WaylandPositioner::Result WaylandPositioner::CalculateBounds(
     const gfx::Rect& work_area,
     bool flip_x,
     bool flip_y) const {
@@ -359,9 +359,10 @@ WaylandPositioner::Result WaylandPositioner::CalculatePosition(
           {work_area.y(), work_area.bottom()},
           {anchor_rect_.y(), anchor_rect_.bottom()}, size_.height(), offset_y,
           anchor_y, gravity_y, adjustments_y);
-  return {{x.first.start, y.first.start},
-          {x.first.end - x.first.start, y.first.end - y.first.start},
-          x.second.flip ? !flip_x : flip_x,
+  gfx::Point origin(x.first.start, y.first.start);
+  gfx::Size size(std::max(1, x.first.end - x.first.start),
+                 std::max(1, y.first.end - y.first.start));
+  return {origin, size, x.second.flip ? !flip_x : flip_x,
           y.second.flip ? !flip_y : flip_y};
 }
 

components/exo/wayland/wayland_positioner.h

@@ -35,10 +35,10 @@ class WaylandPositioner {
 
   WaylandPositioner(Version v) : version_(v) {}
 
-  // Calculate and return position from current state.
-  Result CalculatePosition(const gfx::Rect& work_area,
-                           bool flip_x,
-                           bool flip_y) const;
+  // Calculate and return bounds from current state.
+  Result CalculateBounds(const gfx::Rect& work_area,
+                         bool flip_x,
+                         bool flip_y) const;
 
   void SetSize(gfx::Size size) { size_ = std::move(size); }
 

components/exo/wayland/wayland_positioner_unittest.cc

@@ -58,7 +58,7 @@ class WaylandPositionerTest : public testing::Test {
     }
 
     WaylandPositioner::Result Solve() const {
-      return positioner.CalculatePosition(work_area, flip_x, flip_y);
+      return positioner.CalculateBounds(work_area, flip_x, flip_y);
     }
 
     gfx::Rect SolveToRect() const {
@@ -365,6 +365,27 @@ TEST_F(WaylandPositionerTest, PreventsSlidingThatOccludesAnchorRect) {
             gfx::Rect(1, 1, 4, 4));
 }
 
+// Make sure that the size should never be an empty even if the constraints
+// resulted in empty size.
+TEST_F(WaylandPositionerTest, ResizableShouldNotBeEmpty) {
+  EXPECT_EQ(TestCaseBuilder(WaylandPositioner::Version::STABLE)
+                .SetSize(3, 3)
+                .SetGravity(XDG_POSITIONER_GRAVITY_BOTTOM)
+                .SetAnchor(XDG_POSITIONER_ANCHOR_BOTTOM)
+                .SetAdjustment(~XDG_POSITIONER_CONSTRAINT_ADJUSTMENT_NONE)
+                .SetAnchorRect(1, -10, 4, 4)
+                .SolveToRect(),
+            gfx::Rect(2, 0, 3, 1));
+  EXPECT_EQ(TestCaseBuilder(WaylandPositioner::Version::STABLE)
+                .SetSize(3, 3)
+                .SetGravity(XDG_POSITIONER_GRAVITY_RIGHT)
+                .SetAnchor(XDG_POSITIONER_ANCHOR_RIGHT)
+                .SetAdjustment(~XDG_POSITIONER_CONSTRAINT_ADJUSTMENT_NONE)
+                .SetAnchorRect(-10, 2, 4, 4)
+                .SolveToRect(),
+            gfx::Rect(0, 2, 1, 3));
+}
+
 }  // namespace
 }  // namespace wayland
 }  // namespace exo

components/exo/wayland/xdg_shell.cc

@@ -586,7 +586,7 @@ void xdg_surface_get_popup(wl_client* client,
   // Try layout using parent's flip state.
   WaylandPositioner* positioner =
       GetUserDataAs<WaylandPositioner>(positioner_resource);
-  WaylandPositioner::Result position = positioner->CalculatePosition(
+  WaylandPositioner::Result position = positioner->CalculateBounds(
       work_area, parent_data->shell_surface->x_flipped(),
       parent_data->shell_surface->y_flipped());
 

components/exo/wayland/zxdg_shell.cc

@@ -557,7 +557,7 @@ void xdg_surface_v6_get_popup(wl_client* client,
   // Try layout using parent's flip state.
   WaylandPositioner* positioner =
       GetUserDataAs<WaylandPositioner>(positioner_resource);
-  WaylandPositioner::Result position = positioner->CalculatePosition(
+  WaylandPositioner::Result position = positioner->CalculateBounds(
       work_area, parent_data->shell_surface->x_flipped(),
       parent_data->shell_surface->y_flipped());