MQParser memory leak fix

MQParser memory leak fix

The MQParser failed to free CSSParserValues when a MediaQuery included more than one MediaQueryExpressions.
This CL fixes that.

BUG=369417
Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=173547

[eseidel, 2014-05-07 15:26:09]

https://codereview.chromium.org/277433002/diff/1/Source/core/css/CSSParserVal...
File Source/core/css/CSSParserValues.cpp (right):

https://codereview.chromium.org/277433002/diff/1/Source/core/css/CSSParserVal...
Source/core/css/CSSParserValues.cpp:51: destroy(m_values);
Seems like this could end up destroying twice.  I guess the logic is that
destory i never called w/o clear except here?

Why don't we use a wrapper for CSSParserValue which knows how to destory itself?
 Or perhaps we should just give CSSParserValue a working destructor?

[Yoav Weiss, 2014-05-07 15:34:42]

https://codereview.chromium.org/277433002/diff/1/Source/core/css/CSSParserVal...
File Source/core/css/CSSParserValues.cpp (right):

https://codereview.chromium.org/277433002/diff/1/Source/core/css/CSSParserVal...
Source/core/css/CSSParserValues.cpp:51: destroy(m_values);
On 2014/05/07 15:26:10, eseidel wrote:
> Seems like this could end up destroying twice.  I guess the logic is that
> destory i never called w/o clear except here?
Yeah, and calling destroyAndClear immediately followed by the destructor does
not damage, since m_values would be empty.
> 
> Why don't we use a wrapper for CSSParserValue which knows how to destory
itself?
>  Or perhaps we should just give CSSParserValue a working destructor?
We probably could do that, but since CSSParserValueList has several clients, not
just my code, I'd need to further study what would be the implications of that.

[eseidel, 2014-05-07 15:47:26]

Since other places have clearly had to invent this kind of destruction code can
we just re-use that?

[eseidel, 2014-05-07 15:49:50]

Why is clear ever valid?  Clear appear to just clear out the list and presumably
leak all its contents?

[eseidel, 2014-05-07 15:52:43]

lgtm

[Yoav Weiss, 2014-05-07 16:41:25]

The CQ bit was checked by yoav@yoav.ws

[commit-bot: I haz the power, 2014-05-07 16:42:22]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/yoav@yoav.ws/277433002/20001

[commit-bot: I haz the power, 2014-05-07 17:29:02]

FYI, CQ is re-trying this CL (attempt #1).
Please consider checking whether the failures are real,
and report flakes to chrome-troopers@google.com.
The failing builders are:
  linux_blink_rel on tryserver.blink

[commit-bot: I haz the power, 2014-05-07 18:00:25]

Change committed as 173547