Convert top controls to use DIP instead of PX.

Convert top controls to use DIP instead of PX.

Previously, scroll offset was based on screen pixels, but now
is based on screen density independent pixels.  This converts
the top controls manager to deal in DIP instead of PX.

BUG=161303
Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=180089

[jamesr, 2013-01-31 00:00:11]

lgtm for webkit/compositor_bindings/, rest is up to aelias@

[aelias_OOO_until_Jul13, 2013-01-31 09:53:10]

It might be easier to have the flag take an integer and convert to DIP in the
switch reading?  The top controls refer to an Android thing measured in pixels
over there, I assume.

[Ted C, 2013-01-31 18:22:59]

On 2013/01/31 09:53:10, aelias wrote:
> It might be easier to have the flag take an integer and convert to DIP in the
> switch reading?  The top controls refer to an Android thing measured in pixels
> over there, I assume.

At least currently when parsing the switches, there is no access to the
deviceScaleFactor.  So I would probably need to pass it to
WebLayerTreeViewImpl::initialize to have it set the right value. 

Also the scale factor appears to be mutable in RenderWidget/LayerTreeHostImpl,
which means if I do the conversion from pixels to DP in the renderer then I
should continually update the top controls as the device scale factor changes.

Or am I missing something?

[aelias_OOO_until_Jul13, 2013-01-31 22:43:58]

lgtm

OK, let's go with this as is.

[commit-bot: I haz the power, 2013-01-31 23:03:10]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/tedchoc@chromium.org/12095071/1

[commit-bot: I haz the power, 2013-02-01 05:47:31]

Change committed as 180089