HashMap misuse in ScrollingCoordinator

HashMap misuse in ScrollingCoordinator

The aux 'makeLayerChildFrameMap' function used in the
ScrollingCoordinator should not be allowed to add empty
key values to the given LayerFrameMap, as this is misuse
of WTF::HashMap which leads to undefined behavior (for
example it was the root cause of
http://code.google.com/p/chromium/issues/detail?id=310975 )

Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=170150

[Mikhail, 2014-03-26 15:01:39]

PTAL

[Nico, 2014-03-26 15:48:14]

https://codereview.chromium.org/212813004/diff/1/Source/core/page/scrolling/S...
File Source/core/page/scrolling/ScrollingCoordinator.cpp (right):

https://codereview.chromium.org/212813004/diff/1/Source/core/page/scrolling/S...
Source/core/page/scrolling/ScrollingCoordinator.cpp:398:
map->add(containingLayer, Vector<const
LocalFrame*>()).storedValue->value.append(child);
Should add() ASSERT that the key is non-NULL then?

[Mikhail, 2014-03-26 16:05:57]

On 2014/03/26 15:48:14, Nico wrote:
>
https://codereview.chromium.org/212813004/diff/1/Source/core/page/scrolling/S...
> File Source/core/page/scrolling/ScrollingCoordinator.cpp (right):
> 
>
https://codereview.chromium.org/212813004/diff/1/Source/core/page/scrolling/S...
> Source/core/page/scrolling/ScrollingCoordinator.cpp:398:
> map->add(containingLayer, Vector<const
> LocalFrame*>()).storedValue->value.append(child);
> Should add() ASSERT that the key is non-NULL then?

I would put such assertions rather to HashTable itself (with a separate patch)
so that all the similar cases are caught and to explicitly say that we do not
expect empty or deleted keys. Also we might need a bit more complex HashTable
key check, like WebKit has (pls. see HashTable::checkKey() method there).

[Nico, 2014-03-26 16:08:19]

lgtm

[Mikhail, 2014-03-27 09:03:42]

The CQ bit was checked by mikhail.pozdnyakov@intel.com

[commit-bot: I haz the power, 2014-03-27 09:03:52]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/mikhail.pozdnyakov@intel.com/212813004/1

[commit-bot: I haz the power, 2014-03-27 09:04:11]

Change committed as 170150