Return width from drawText to stop re-measure in Canvas

Return width from drawText to stop re-measure in Canvas

Allowing drawText to return width of what was drawn, 
so that we don't have to make call to width to 
re-measure in Canvas drawing.

R=eae@chromium.org
BUG=410706
TEST=TEST=fast/canvas/canvas-drawtext-width-return.html

Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=181703

[h.joshi, 2014-09-04 07:00:37]

Patchset #3 (id:40001) has been deleted

[h.joshi, 2014-09-04 07:20:16]

Patchset #2 (id:20001) has been deleted

[h.joshi, 2014-09-04 09:09:45]

Patchset #2 (id:60001) has been deleted

[h.joshi, 2014-09-04 11:24:37]

h.joshi@samsung.com changed reviewers:
+ behdad@chromium.org, eae@chromium.org

[h.joshi, 2014-09-08 13:23:13]

eae/bendad: Pls review

[h.joshi, 2014-09-08 13:23:52]

Sorry for the typo:
@eae/behdad: Pls review

[eae, 2014-09-08 14:34:46]

Is this guaranteed to always return the same width as re-measuring it would?
Would be nice to see some kind of test coverage for this. Be it a unit or layout
test stressing the edge cases.

[h.joshi, 2014-09-09 12:03:55]

Yes drawText will return same width as "font.width", I tested with different 
string as well (complex and simple). Plus in case they return different width 
then we could have issues in normal layout/rendering as well.
 As "font.width" is called at layout phase which helps to decide element
position.

Adding Layout Test case, which checks Simple and Complex path.
Please suggest if test case is fine or some thing more is required.

One more thing, in case user tried to draw more string (specially mixed LTR/RTL)

then Performace improvement could also be seen as call to "font.width" is not
made.

[eae, 2014-09-09 19:27:36]

LGTM
Thanks for the explanation and adding the test. I updated the description
accordingly.

[h.joshi, 2014-09-10 02:38:40]

Thank you Emil.

[h.joshi, 2014-09-10 02:38:51]

The CQ bit was checked by h.joshi@samsung.com

[commit-bot: I haz the power, 2014-09-10 02:40:23]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/h.joshi@samsung.com/519373002/100001

[commit-bot: I haz the power, 2014-09-10 04:41:00]

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

[commit-bot: I haz the power, 2014-09-10 04:41:01]

Exceeded time limit waiting for builds to trigger.

[h.joshi, 2014-09-10 05:04:18]

The CQ bit was checked by h.joshi@samsung.com

[commit-bot: I haz the power, 2014-09-10 05:04:42]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/h.joshi@samsung.com/519373002/120001

[commit-bot: I haz the power, 2014-09-10 06:12:37]

Committed patchset #4 (id:120001) as 181703