Android: In-place URL loading for Preview Tab

Clicking on a link that would open a new tab should just navigate to
that website when the link is clicked in a preview tab.

The request for urls to be opened in a new tab goes through
WebContentsDelegate |shouldCreateWebContents| -> |webContentsCreated|
-> |addNewContents|. This CL handles it by having
|shouldCreateWebContents| return false so that no new WebContents
object is created. The passed URL is loaded into the preview
tab instead.

Bug: 1014777
Change-Id: If4fd76f563427aaae230af4e0519c2c388791fa5
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1954990Reviewed-by: Donn Denman <donnd@chromium.org>
Commit-Queue: Jinsuk Kim <jinsukkim@chromium.org>
Cr-Commit-Position: refs/heads/master@{#722682}

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

@@ -219,6 +219,12 @@ public class OverlayPanelContent {
                 mContentDelegate.onOpenNewTabRequested(url);
             }
 
+            @Override
+            public boolean shouldCreateWebContents(String targetUrl) {
+                mContentDelegate.onOpenNewTabRequested(targetUrl);
+                return false;
+            }
+
             @Override
             public int getTopControlsHeight() {
                 return (int) (mBarHeightPx