MacViews: Handle System colors that have no alpha channel

MacViews: Handle System colors that have no alpha channel

Sometimes, [NSColor controlColor] returns "white". With no alpha. This
causes a failed CHECK().

This should be covered by NativeThemeMacTest.SystemColorsExist, but
AppKit doesn't cooperate there. In native_theme_unittests,
native_theme->GetSystemColor(kColorId_UnfocusedBorderColor) always gives
0xffe8e8e8. However, in the same Chrome process [NSColor controlColor]
can return both 0x??ffffff and 0xffe8e8e8 when opening up the
toolkit-views task manager.

This is probably an AppKit bug, but we shouldn't trust AppKit to give us
alpha channels anyway. So, this CL adds handling for single-component
system colors.

BUG=424040, 379086
Committed: https://crrev.com/d339eed0928759ab8082dd9944541699bea97512
Cr-Commit-Position: refs/heads/master@{#300066}

[tapted, 2014-10-16 05:05:45]

tapted@chromium.org changed reviewers:
+ avi@chromium.org

[tapted, 2014-10-16 11:07:28]

Hi Avi, please take a look. (I think this is needed regardless, but I might need
a further workaround for http://crbug.com/424040 :/ )

[Avi (use Gerrit), 2014-10-16 15:13:40]

lgtm

https://codereview.chromium.org/658033002/diff/20001/ui/native_theme/native_t...
File ui/native_theme/native_theme_mac.mm (right):

https://codereview.chromium.org/658033002/diff/20001/ui/native_theme/native_t...
ui/native_theme/native_theme_mac.mm:107: // is easy (RGB to grayscale is less
easy).
Update comment?

[tapted, 2014-10-17 04:18:52]

Thanks Avi!

https://codereview.chromium.org/658033002/diff/20001/ui/native_theme/native_t...
File ui/native_theme/native_theme_mac.mm (right):

https://codereview.chromium.org/658033002/diff/20001/ui/native_theme/native_t...
ui/native_theme/native_theme_mac.mm:107: // is easy (RGB to grayscale is less
easy).
On 2014/10/16 15:13:40, Avi wrote:
> Update comment?

Done.

[tapted, 2014-10-17 04:18:56]

The CQ bit was checked by tapted@chromium.org

[commit-bot: I haz the power, 2014-10-17 04:19:40]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/658033002/40001

[commit-bot: I haz the power, 2014-10-17 04:59:06]

Committed patchset #3 (id:40001)

[commit-bot: I haz the power, 2014-10-17 05:00:47]

Patchset 3 (id:??) landed as
https://crrev.com/d339eed0928759ab8082dd9944541699bea97512
Cr-Commit-Position: refs/heads/master@{#300066}