Make sure user can always get to next page with keyboard.

There's a case where hitting the left/right arrow in the first/last
column wouldn't give focus to an icon on the next page because it is
vertically too far from the first icon to be considered. This makes
for a bad user experience, because there is no way to switch pages
with the keyboard. So now we brute-force search for an appropriate
icon if none was found in this case.

Bug: 25434120
Change-Id: Ifdead0e3b458717ccb33e2f0ec7c15f1fcce4b95

src/com/android/launcher3/util/FocusLogic.java

@@ -346,6 +346,18 @@ public class FocusLogic {
                 }
             }
         }
+
+        // Rule 3: if switching between pages, do a brute-force search to find an item that was
+        //         missed by rules 1 and 2 (such as when going from a bottom right icon to top left)
+        if (iconIdx == PIVOT) {
+            for (int x = xPos + increment; 0 <= x && x < cntX; x = x + increment) {
+                for (int y = 0; y < cntY; y++) {
+                    if ((newIconIndex = inspectMatrix(x, y, cntX, cntY, matrix)) != NOOP) {
+                        return newIconIndex;
+                    }
+                }
+            }
+        }
         return newIconIndex;
     }