Timeline: extract TimelineView from TimelinePanel class.

The API methods of TimelineView:
show
windowChanged
createFilters
searchableView
supportsGlueParentMode
glueParentModeChanged
modeChanged
overviewControl

The API methods and properties of TimelinePanel

recordsCounter
setWindow
setSizebarWidth
recordingInProgress

BUG=
R=caseq@chromium.org

Review URL: https://codereview.chromium.org/117863004

git-svn-id: svn://svn.chromium.org/blink/trunk@164289 bbb929c8-8fbe-4397-9dbb-9b2b20218538