MacViews: Enable RenderTextHarfBuzz to get Textfields to work.

MacViews: Enable RenderTextHarfBuzz to get Textfields to work.

Textfields require RenderTextHarfBuzz to work properly on the Mac because
RenderTextMac's implementation is not complete.
But RenderTextMac is used by the Cocoa UI to perform string sizing and elliding,
HarfBuzz will not give the same answers.
So for now we turn on HarfBuzz conditionally on OS_MACOSX and TOOLKIT_VIEWS.
TextFieldModel and StyledLabel unit tests now pass without failures.

BUG=378134
Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=276341

[msw, 2014-06-10 23:23:47]

lgtm with a minor optional nit.

https://codereview.chromium.org/326093004/diff/1/ui/gfx/render_text.cc
File ui/gfx/render_text.cc (right):

https://codereview.chromium.org/326093004/diff/1/ui/gfx/render_text.cc#newcod...
ui/gfx/render_text.cc:416: // views::Textfield requires RenderTextHarfBuzz on
Mac because RenderTextMac's
nit: Textfield is the heaviest user, but I'm planning on converting views::Label
to cache RenderText instances. You could generalize the comment to something
like "Use the more complete HarfBuzz implementation for Views controls on Mac."

[Andre, 2014-06-10 23:41:17]

The CQ bit was checked by andresantoso@chromium.org

[commit-bot: I haz the power, 2014-06-10 23:45:03]

CQ is trying da patch. Follow status at

https://chromium-status.appspot.com/cq/andresantoso@chromium.org/326093004/20001

[commit-bot: I haz the power, 2014-06-11 11:02:04]

Change committed as 276341