Make RenderTextHarfBuzz examine full font list.

ui/gfx/render_text_unittest.cc

Index: ui/gfx/render_text_unittest.cc
diff --git a/ui/gfx/render_text_unittest.cc b/ui/gfx/render_text_unittest.cc
index 1c6f902d936fb435827912df67561e1d1af51c51..c67f9e973070cdf5b590a9fb014c7e181a3f5b66 100644
--- a/ui/gfx/render_text_unittest.cc
+++ b/ui/gfx/render_text_unittest.cc
@@ -2326,4 +2326,29 @@ TEST_F(RenderTextTest, StringFitsOwnWidth) {
   EXPECT_EQ(kString, render_text->GetLayoutText());
 }
 
+// Ensure that RenderText examines all of the fonts in its FontList before
+// falling back to other fonts.
+TEST_F(RenderTextTest, FontListFallback) {

[Daniel Erat, 2014/10/24 15:43:23]

not sure yet whether this will work on all platforms. i may also need to change
it to explicitly ask for RenderTextHarfBuzz.

[msw, 2014/10/24 16:09:11]

Acknowledged.

+  // Double-check that the requested fonts are present.
+  FontList font_list("Arial, Symbol, 12px");
+  const std::vector<Font>& fonts = font_list.GetFonts();
+  ASSERT_EQ(2u, fonts.size());
+  ASSERT_EQ("arial",
+            base::StringToLowerASCII(fonts[0].GetActualFontNameForTesting()));
+  ASSERT_EQ("symbol",
+            base::StringToLowerASCII(fonts[1].GetActualFontNameForTesting()));
+
+  // "⊕" (CIRCLED PLUS) should be rendered with Symbol rather than falling back

[msw, 2014/10/24 16:09:11]

Can you actually include this unicode char in this (ASCII?) file?

[Daniel Erat, 2014/10/24 16:25:47]

the web is inconclusive here, but i think it's fine for us within comments. i
only did it because i saw that an earlier test in this file includes "®"
(REGISTERED SIGN) in a comment. :-P

[msw, 2014/10/24 16:48:29]

Hmm, the style guide might suggest only UTF-8 and not UTF-16?
https://engdoc.corp.google.com/eng/doc/devguide/cpp/styleguide.shtml?cl=head#...
Otherwise, if pre-submit and lint don't complain, this is good to know, and
there are probably many other cases then where I've included the UTF-8 or
escaped chars in comments, but an actual symbol would be so much more useful!

+  // to some other font that's present on the system.
+  scoped_ptr<RenderText> render_text(RenderText::CreateInstance());
+  render_text->SetFontList(font_list);
+  render_text->SetText(UTF8ToUTF16("\xE2\x8A\x95"));
+  Canvas canvas;
+  render_text->Draw(&canvas);

[msw, 2014/10/24 16:09:11]

You shouldn't need to Draw, GetFontSpansForTesting will EnsureLayout.

[Daniel Erat, 2014/10/24 16:25:47]

cool, thanks. done.

+  const std::vector<RenderText::FontSpan> spans =
+      render_text->GetFontSpansForTesting();
+  ASSERT_EQ(static_cast<size_t>(1), spans.size());
+  EXPECT_EQ("Symbol", spans[0].first.GetFontName());

[msw, 2014/10/24 16:09:11]

Does this actually fail without your change?

[Daniel Erat, 2014/10/24 16:25:47]

yep, wrote the test first. :-P at least on my gtrusty workstation, RTHB falls
back to DejaVu Sans instead of using Symbol without my change.

[msw, 2014/10/24 16:48:29]

Acknowledged.

+}
+
 }  // namespace gfx