Add a move constructor and move assignment operator to Length

Add a move constructor and move assignment operator to Length

Add a move constructor and move assignment operator to Length for
performance.

This is inspired by the following WebKit revision by andersca@apple.com:
http://trac.webkit.org/changeset/156132

R=tkent@chromium.org

Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=174830

[tkent, 2014-05-27 00:13:28]

https://codereview.chromium.org/296403003/diff/1/Source/platform/Length.h
File Source/platform/Length.h (right):

https://codereview.chromium.org/296403003/diff/1/Source/platform/Length.h#new...
Source/platform/Length.h:127: length.m_type = Auto;
Why do we need do length.m_type=Auto though |length| is rvalue?

https://codereview.chromium.org/296403003/diff/1/Source/platform/Length.h#new...
Source/platform/Length.h:139: length.m_type = Auto;
Ditto.

I understand length.incrementCalculatedRef() is unnecessary in this case.

[Inactive, 2014-05-27 00:33:28]

https://codereview.chromium.org/296403003/diff/1/Source/platform/Length.h
File Source/platform/Length.h (right):

https://codereview.chromium.org/296403003/diff/1/Source/platform/Length.h#new...
Source/platform/Length.h:127: length.m_type = Auto;
On 2014/05/27 00:13:29, tkent wrote:
> Why do we need do length.m_type=Auto though |length| is rvalue?
> 
> 

We basically want to make sure that |length|'s destructor won't call
decrementCalculatedRef() (as isCalculated() check will fail) since we don't call
length.incrementCalculatedRef() here.

[tkent, 2014-05-27 00:41:58]

lgtm

On 2014/05/27 00:33:28, Chris Dumez wrote:
> https://codereview.chromium.org/296403003/diff/1/Source/platform/Length.h
> File Source/platform/Length.h (right):
> 
>
https://codereview.chromium.org/296403003/diff/1/Source/platform/Length.h#new...
> Source/platform/Length.h:127: length.m_type = Auto;
> On 2014/05/27 00:13:29, tkent wrote:
> > Why do we need do length.m_type=Auto though |length| is rvalue?
> > 
> > 
> 
> We basically want to make sure that |length|'s destructor won't call
> decrementCalculatedRef() (as isCalculated() check will fail) since we don't
call
> length.incrementCalculatedRef() here.

Thanks, I understand.  Adding code comments would be helpful.

[Inactive, 2014-05-27 00:45:50]

On 2014/05/27 00:41:58, tkent wrote:
> lgtm
> 
> On 2014/05/27 00:33:28, Chris Dumez wrote:
> > https://codereview.chromium.org/296403003/diff/1/Source/platform/Length.h
> > File Source/platform/Length.h (right):
> > 
> >
>
https://codereview.chromium.org/296403003/diff/1/Source/platform/Length.h#new...
> > Source/platform/Length.h:127: length.m_type = Auto;
> > On 2014/05/27 00:13:29, tkent wrote:
> > > Why do we need do length.m_type=Auto though |length| is rvalue?
> > > 
> > > 
> > 
> > We basically want to make sure that |length|'s destructor won't call
> > decrementCalculatedRef() (as isCalculated() check will fail) since we don't
> call
> > length.incrementCalculatedRef() here.
> 
> Thanks, I understand.  Adding code comments would be helpful.

Done.

[Inactive, 2014-05-27 00:46:23]

The CQ bit was checked by ch.dumez@samsung.com

[commit-bot: I haz the power, 2014-05-27 00:46:29]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/ch.dumez@samsung.com/296403003/20001

[commit-bot: I haz the power, 2014-05-27 02:02:23]

Change committed as 174830