Notify the browser when the page lost interest about gamepads

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. For gamepad that is not perfect where the
the page can ask the gamepad state anytime via navigator.getGamepads().
This CL doesn't change visible behavior thus no tests. The enhancement is that
now we properly tell the browser that we are not intereseted in gamepads while
we are hidden so it can suspend the polling thread. Visibility related tests
should be added for gamepad though, I will do that later.

This is a fixed reland of r176618

BUG=386846
R=abarth@chromium.org

Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=176789

[kbalazs, 2014-06-20 23:25:53]

This was reverted because it broke content_browsertests. The problem was that by
simply omitting to check m_hasEventListener in pageVisibilityChanged I told the
browser that we are watching gamepads even before anyone would ask for any
gamepad data via navigator.getGamepads() or by listening on gamepadconnected.
And apparently the chromium code doesn't expect that this stuff can be called
for a unit test (when a MockRenderThread is instantiated and not a
RenderThreadImpl) which is kind of a bug itself but that's another thing.

[abarth-chromium, 2014-06-21 05:40:17]

https://codereview.chromium.org/332183009/diff/1/Source/modules/gamepad/Navig...
File Source/modules/gamepad/NavigatorGamepad.cpp (right):

https://codereview.chromium.org/332183009/diff/1/Source/modules/gamepad/Navig...
Source/modules/gamepad/NavigatorGamepad.cpp:237: if (page()->visibilityState()
== PageVisibilityStateVisible && (m_hasEventListener || m_wasPolled))
Instead of m_wasPolled, can we use m_gamepads || m_webkitGamepads ?

[kbalazs, 2014-06-23 19:16:37]

On 2014/06/21 05:40:17, abarth wrote:
>
https://codereview.chromium.org/332183009/diff/1/Source/modules/gamepad/Navig...
> File Source/modules/gamepad/NavigatorGamepad.cpp (right):
> 
>
https://codereview.chromium.org/332183009/diff/1/Source/modules/gamepad/Navig...
> Source/modules/gamepad/NavigatorGamepad.cpp:237: if (page()->visibilityState()
> == PageVisibilityStateVisible && (m_hasEventListener || m_wasPolled))
> Instead of m_wasPolled, can we use m_gamepads || m_webkitGamepads ?

Yep, we can do that, done.

[abarth-chromium, 2014-06-23 19:59:25]

lgtm

[kbalazs, 2014-06-23 21:22:01]

The CQ bit was checked by b.kelemen@samsung.com

[commit-bot: I haz the power, 2014-06-23 21:22:15]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/b.kelemen@samsung.com/332183009/20001

[commit-bot: I haz the power, 2014-06-23 22:12:02]

FYI, CQ is re-trying this CL (attempt #1).
The failing builders are:
  win_blink_rel on tryserver.blink
(http://build.chromium.org/p/tryserver.blink/builders/win_blink_rel/builds/13191)

[commit-bot: I haz the power, 2014-06-23 22:50:01]

Change committed as 176789