webview: deflake testRequestImageRef.

On devices with gesture navigation, the point on the screen where
WebViewTest#testRequestImageRef was tapping was very close to the edge
and sometimes overlapped with the region used for gesture recognition,
causing an event injection failure since the test doesn't own the
gesture recognition window.

Make the image we're trying to tap on the full width and height of the
WebView (since its size/location doesn't really matter for this test)
and send the tap event to the center of the view instead, where it
should avoid any special edge gesture regions.

Fixes: 174245348
Test: atest android.webkit.cts.WebViewTest#testRequestImageRef
Change-Id: Ia437a1e649710ee91bf6d7dfb9c51e17096ea0cf
1 file changed