Resolve Coverity Scan findings

[kalyankondapally]

I submitted our Milestone branch to CoverityScan [a] and had three findings from the tool:

event_converter_in_process.cc:

1. Uninitialized variable output_observer_.

2)window_tree_host_delegate_wayland.cc (line 88)
. return_iterator: "this->open_windows()->begin()" returns an iterator for "this->open_windows()".

CID 1177784 (#1 of 1): Iterator container mismatch (MISMATCHED_ITERATOR)5. mismatched_iterator: Using iterator "this->open_windows()->begin()" from "this->open_windows()" with "windows".
3)keyboard_code_conversion.cc

CID 1177245 (#3 of 3): Inferred misuse of enum (MIXED_ENUMS)mixed_enums: Mixing enum types ui::KeyboardCode and ozonewayland::OZONECHARCODE for "keysym".

This issue is about fixing this first 2.

a) https://scan.coverity.com/projects/1437

[kalyankondapally]

For first issue:
kalyankondapally@f30b07b

For second issue:
kalyankondapally@bd92b18

@tiagovignatti PTAL

[kalyankondapally]

@tiagovignatti We can even have a coverity badge to our README file now if we want to, it would look like this here: https://github.com/kalyankondapally/ozone-wayland/tree/master-polltest (Check the end of ReadMe file)

[tiagovignatti]

cool, the coverity badge looks cute :) both patches LGTM. Thanks.

[kalyankondapally]

Merged 09764e6
6ecb6ae