[Win, Linux] Always display the avatar button text at the same size.

The problem is that some locales (Hindi) or platforms (Linux) have a
bigger base font size for the default font (crbug.com/405994). If this
is the case, we should decrease the font size to the one we expect,
so that the font fits in the button correctly.

Just adjusting the baseline is not always enough, as the new avatar
button has a fixed size, and the text might not fit correctly
regardless of the baseline adjustments.

Screenshots: https://drive.google.com/folderview?id=0B1B1Up4p2NRMRHc5WTBxZWNrRm8&usp=sharing

BUG=403466
TEST=Start Chrome with --enable-new-avatar-menu on Linux, or with --enable-new-avatar-menu and --lang-hi on Windows. The avatar button text should fit nicely in the button.

Review URL: https://codereview.chromium.org/470053004

Cr-Commit-Position: refs/heads/master@{#292715}

1 files changed, 25 insertions, 0 deletions

diff --git a/ui/gfx/font_list.h b/ui/gfx/font_list.h
index 1ba8ad1..bc3afc2 100644
--- a/ui/gfx/font_list.h
+++ b/ui/gfx/font_list.h
@@ -83,6 +83,31 @@ class GFX_EXPORT FontList {
   // values: Font::BOLD, Font::ITALIC and Font::UNDERLINE.
   FontList DeriveWithStyle(int font_style) const;
 
+  // Shrinks the font size until the font list fits within |height| while
+  // having its cap height vertically centered. Returns a new FontList with
+  // the correct height.
+  //
+  // The expected layout:
+  //   +--------+-----------------------------------------------+------------+
+  //   |        | y offset                                      | space      |
+  //   |        +--------+-------------------+------------------+ above      |
+  //   |        |        |                   | internal leading | cap height |
+  //   | box    | font   | ascent (baseline) +------------------+------------+
+  //   | height | height |                   | cap height                    |
+  //   |        |        |-------------------+------------------+------------+
+  //   |        |        | descent (height - baseline)          | space      |
+  //   |        +--------+--------------------------------------+ below      |
+  //   |        | space at bottom                               | cap height |
+  //   +--------+-----------------------------------------------+------------+
+  // Goal:
+  //     center of box height == center of cap height
+  //     (i.e. space above cap height == space below cap height)
+  // Restrictions:
+  //     y offset >= 0
+  //     space at bottom >= 0
+  //     (i.e. Entire font must be visible inside the box.)
+  gfx::FontList DeriveWithHeightUpperBound(int height) const;
+
   // Returns the height of this font list, which is max(ascent) + max(descent)
   // for all the fonts in the font list.
   int GetHeight() const;