Revert of Notify the browser when the page lost interest about gamepads (https://codereview.chromium.org/345013002/)

Reason for revert:
Causing content_browsertest crashes on all platforms

Original issue's description:
> Notify the browser when the page lost interest about gamepads
> 
> The page visibility logic used in NavigatorGamepad via DeviceEventControllerBase
> assumes that we only want to tell the dispatcher that we are uninterested in
> events if we have an event listener. This is not perfect for gamepad. If the
> page doesn't add event listener for gamepad events it can still poll the data
> via navigator.getGamepads() at which point we tell the browser that we need
> gamepad data. We also want to tell the browser if we are not interested so that
> it can suspend the polling thread.
> Long story short, we shouldn't check m_hasEventListener in
> pageVisibilityChanged. This CL doesn't change visible behavior thus no tests.
> Visibility related tests should be added for gamepad though, I will do that
> later.
> 
> BUG=386846
> 
> R=bajones@chromium.org
> TBR=abarth@chromium.org
> 
> NOTRY=true
> 
> Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=176618

TBR=abarth@chromium.org,bajones@chromium.org,b.kelemen@samsung.com
NOTREECHECKS=true
NOTRY=true
BUG=386846

Review URL: https://codereview.chromium.org/348083003

git-svn-id: svn://svn.chromium.org/blink/trunk@176635 bbb929c8-8fbe-4397-9dbb-9b2b20218538