[Home] Disallow half-height on small screens

If BottomSheet#setSheetState() is called with SHEET_STATE_HALF on a
small screen, change the target state to SHEET_STATE_FULL since half
state is not valid.

BUG=726012

Change-Id: Ie14738718954e4ac77273708ae5c2f3a610a2603
Reviewed-on: https://chromium-review.googlesource.com/531345
Commit-Queue: Matthew Jones <mdjones@chromium.org>
Reviewed-by: Matthew Jones <mdjones@chromium.org>
Cr-Commit-Position: refs/heads/master@{#478671}

chrome/android/java/src/org/chromium/chrome/browser/widget/bottomsheet/BottomSheet.java

@@ -1124,6 +1124,10 @@ public class BottomSheet
      */
     public void setSheetState(@SheetState int state, boolean animate) {
         assert state != SHEET_STATE_SCROLLING && state != SHEET_STATE_NONE;
+
+        // Half state is not valid on small screens.
+        if (state == SHEET_STATE_HALF && isSmallScreen()) state = SHEET_STATE_FULL;
+
         mTargetState = state;
 
         cancelAnimation();