Fix problems with StyledLabel::CalculatePreferredSize().

Calling GetPreferredSize() on a label which hadn't otherwise computed a layout
would return an empty size, which seems wrong.

Calling GetHeightForWidth() (a const method) could change the results of
GetPreferredSize(), a violation of logical constness.

Bug: none
Change-Id: I2729b9d83ffa94e368fb6553e9ead4b2646e01c2
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1884360
Commit-Queue: Peter Kasting <pkasting@chromium.org>
Reviewed-by: Trent Apted <tapted@chromium.org>
Cr-Commit-Position: refs/heads/master@{#710622}

ui/views/controls/styled_label.cc

@@ -213,8 +213,8 @@ void StyledLabel::GetAccessibleNodeData(ui::AXNodeData* node_data) {
 }
 
 gfx::Size StyledLabel::CalculatePreferredSize() const {
-  // TODO(pkasting): This seems suspicious; shouldn't there be a call to
-  // CalculateLayout(std::numeric_limits<int>::max()) here?
+  // Respect any existing size.  If there is none, default to a single line.
+  CalculateLayout((width() == 0) ? std::numeric_limits<int>::max() : width());
   return layout_size_info_.total_size;
 }
 

ui/views/controls/styled_label_unittest.cc

@@ -776,4 +776,34 @@ TEST_F(StyledLabelTest, SizeToFit) {
   EXPECT_EQ(1000, styled()->children().front()->bounds().right());
 }
 
+// Verifies that a non-empty label has a preferred size by default.
+TEST_F(StyledLabelTest, PreferredSizeNonEmpty) {
+  const std::string text("text");
+  InitStyledLabel(text);
+  EXPECT_FALSE(styled()->GetPreferredSize().IsEmpty());
+}
+
+// Verifies that GetPreferredSize() respects the existing wrapping.
+TEST_F(StyledLabelTest, PreferredSizeRespectsWrapping) {
+  const std::string text("Long text that can be split across lines");
+  InitStyledLabel(text);
+  gfx::Size size = styled()->GetPreferredSize();
+  size.set_width(size.width() / 2);
+  size.set_height(styled()->GetHeightForWidth(size.width()));
+  styled()->SetSize(size);
+  styled()->Layout();
+  const gfx::Size new_size = styled()->GetPreferredSize();
+  EXPECT_LE(new_size.width(), size.width());
+  EXPECT_EQ(new_size.height(), size.height());
+}
+
+// Verifies that calling a const method does not change the preferred size.
+TEST_F(StyledLabelTest, PreferredSizeAcrossConstCall) {
+  const std::string text("Long text that can be split across lines");
+  InitStyledLabel(text);
+  const gfx::Size size = styled()->GetPreferredSize();
+  styled()->GetHeightForWidth(size.width() / 2);
+  EXPECT_EQ(size, styled()->GetPreferredSize());
+}
+
 }  // namespace views