Update test path to image-decoders.

This needed to be updated to match the file move in
https://codereview.chromium.org/99103006

BUG=303332
TBR=schenneyey@chromium.org
NOTRY=true

Review URL: https://codereview.chromium.org/106423004

git-svn-id: svn://svn.chromium.org/blink/trunk@163525 bbb929c8-8fbe-4397-9dbb-9b2b20218538
DevTools: Timeline: remove TimelinePresentationModel.Category dependency from TimelineOverviewPane

TOP has nothing in common with TPM.Categories. So we can move that code
to the TimelineEventsOverview which is only affected class.

TOP created Overviews each time when user selected other presentation.
In combination with listeners in TimelineEventsOverview that would be a reason of a memory leak.
Also it was unnecessary because we have only one overview of each type.

BUG=none
R=pfeldman@chromium.org

Review URL: https://codereview.chromium.org/111453002

git-svn-id: svn://svn.chromium.org/blink/trunk@163526 bbb929c8-8fbe-4397-9dbb-9b2b20218538