Remove white patch on contextual search

Contextual search needs a full screen height to display its
contents but the height returned from the class OverlayPanelBase
was shorter by toolbar height. This CL sets it right.

Tested on mobile/tablet in both portrait/landscape mode.

Bug: 772205, 810297
Change-Id: I8a863ee2e53075a31d9dc8d61bd8482aa8454455
Reviewed-on: https://chromium-review.googlesource.com/910128
Commit-Queue: Jinsuk Kim <jinsukkim@chromium.org>
Reviewed-by: Donn Denman <donnd@chromium.org>
Reviewed-by: Matthew Jones <mdjones@chromium.org>
Cr-Commit-Position: refs/heads/master@{#537573}

chrome/android/java/src/org/chromium/chrome/browser/compositor/bottombar/OverlayPanelBase.java

@@ -335,7 +335,7 @@ abstract class OverlayPanelBase {
      * @return The height of the Overlay Panel Content View in pixels.
      */
     public int getContentViewHeightPx() {
-        return Math.round((mMaximumHeight - getToolbarHeight()) / mPxToDp);
+        return Math.round(mMaximumHeight / mPxToDp);
     }
 
     // ============================================================================================