Fix shadowing between gfx::ITALIC and gfx::Font::ITALIC

With the shadowing warning enabled and a sufficiently new clang, there
will be warnings about gfx::Font::ITALIC (and STRIKE and UNDERSCORE)
shadowing gfx::ITALIC, coming from the enum gfx::TextStyle. To prevent
that shadowing, this renames the gfx enum values TEXT_STYLE_*,
including a new name, TEXT_STYLE_COUNT, for what would otherwise be
TEXT_STYLE_NUM_TEXT_STYLES.

This shadowing problem currently prevents content (where the shadowing
warning is already enabled) from using these headers together.

Fixes to other shadowing problems, including enabling the shadow
warning, will come in
https://chromium-review.googlesource.com/c/chromium/src/+/1421104
after this has landed.

Bug: 923078,794619
Change-Id: I3018054f06a2fd2dc04cc4e0e72e5a0d641e99c5
Reviewed-on: https://chromium-review.googlesource.com/c/1424799
Auto-Submit: Daniel Bratell <bratell@opera.com>
Reviewed-by: Tibor Goldschwendt <tiborg@chromium.org>
Reviewed-by: Michael Wasserman <msw@chromium.org>
Commit-Queue: Daniel Bratell <bratell@opera.com>
Cr-Commit-Position: refs/heads/master@{#625230}
11 files changed