Reland: Use labels to display views tab titles.

Reland: Use labels to display views tab titles.

The original r276450 was reverted in r276476 for leaks:
http://build.chromium.org/p/chromium.memory/builders/Linux%20ASan%20LSan%20Tests%20%283%29/builds/3954
Fixed here by calling AddChildView(title_) on Tab (duh).

Add a Label view to Tab for displaying the title.
Remove Tab::PaintTitle, bounds and font members.
Remove unnecessary Tab::Get[Title|Icon]Bounds helpers.
Update the text on Tab::SetData, not during paint.
Use gfx::DirectionalityMode, remove the Label enum.

Add gfx::ALIGN_TO_HEAD to gfx::HorizontalAlignment.
Add Label::GetHorizontalAlignment for ALIGN_TO_HEAD.
Always flip left/right in Label::SetHorizontalAlignment.
Have Tab and MessageBoxView use ALIGN_TO_HEAD.

Update comments and tests, related minor cleanup.

TODO: Make Label cache RenderText objects.
TODO: Make RenderText support ALIGN_TO_HEAD.

BUG=240037
TEST=No visible Views tab title changes.
R=sky@chromium.org

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=276566

[msw, 2014-06-11 20:20:11]

Hey Scott, please take a look; thanks!

[sky, 2014-06-11 20:29:56]

LGTM

[msw, 2014-06-11 20:31:30]

The CQ bit was checked by msw@chromium.org

[commit-bot: I haz the power, 2014-06-11 20:36:02]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/msw@chromium.org/329813003/20001

[commit-bot: I haz the power, 2014-06-11 22:00:09]

FYI, CQ is re-trying this CL (attempt #1).
The failing builders are:
  ios_dbg_simulator on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/ios_dbg_simulator/bui...)
  ios_rel_device on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/ios_rel_device/builds...)
  ios_rel_device_ninja on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/ios_rel_device_ninja/...)
  mac_chromium_compile_dbg on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/mac_chromium_compile_...)
  mac_chromium_rel on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/mac_chromium_rel/buil...)
  win_chromium_compile_dbg on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/win_chromium_compile_...)
  win_chromium_rel on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/win_chromium_rel/buil...)
  win_chromium_x64_rel on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/win_chromium_x64_rel/...)
  mac_gpu on tryserver.chromium.gpu
(http://build.chromium.org/p/tryserver.chromium.gpu/builders/mac_gpu/builds/15620)
  win_gpu on tryserver.chromium.gpu
(http://build.chromium.org/p/tryserver.chromium.gpu/builders/win_gpu/builds/18758)

[commit-bot: I haz the power, 2014-06-11 22:18:22]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2014-06-11 22:18:23]

Try jobs failed on following builders:
  mac_chromium_compile_dbg on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/mac_chromium_compile_...)

[msw, 2014-06-12 03:32:37]

The CQ bit was checked by msw@chromium.org

[commit-bot: I haz the power, 2014-06-12 03:33:32]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/msw@chromium.org/329813003/20001

[commit-bot: I haz the power, 2014-06-12 07:41:51]

Change committed as 276566