PlatformEventDispatcher::DispatchEvent() should return a PostDispatchAction

PlatformEventDispatcher::DispatchEvent() should return a PostDispatchAction

Declaring DispatchEvent() as returning a uint32_t when it actually
hands back a PostDispatchAction results in intermingling enum values
with integer types. This causes -Wtype-limits to throw warnings on
some compilers. Declaring the return type appropriately fixes this.

BUG=424334
TEST=ui_unittests
R=sky@chromium.org

bah

[Chris Masone, 2014-10-20 22:24:33]

Sky, how about this approach instead? It seems like the API just has
implementors return one of the enumerated values, as opposed to allowing the
values to be bitwise-ORed together? So this keeps the enum and just makes the
method actually return one of the enumerated values.

This is an alternative to https://codereview.chromium.org/666673005/

[Chris Masone, 2014-10-20 22:27:22]

On 2014/10/20 22:24:33, Chris Masone wrote:
> Sky, how about this approach instead? It seems like the API just has
> implementors return one of the enumerated values, as opposed to allowing the
> values to be bitwise-ORed together? So this keeps the enum and just makes the
> method actually return one of the enumerated values.
> 
> This is an alternative to https://codereview.chromium.org/666673005/

Hrm. This might not work. Bah!