Clear the DropdownViewInfoBuilder state only on focus lost.

This change addresses the issue where zero suggestions are received
ahead of onUrlFocusChange call being completed.
As a result, both deferred keyboard popup and subsequent keyboard
management may cease to function in the zero prefix state.

Bug: 1109330
Change-Id: I5ff5c2ee2103b38ecf9c1b7d8cd53136b1f1a256
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2318312
Commit-Queue: Krishna Govind <govind@chromium.org>
Reviewed-by: Ted Choc <tedchoc@chromium.org>
Cr-Commit-Position: refs/heads/master@{#791349}

chrome/android/java/src/org/chromium/chrome/browser/omnibox/suggestions/DropdownItemViewInfoListBuilder.java

@@ -206,7 +206,10 @@ class DropdownItemViewInfoListBuilder {
             mImageFetcher.clear();
         }
 
-        mBuiltListHasFullyConcealedElements = false;
+        if (!hasFocus) {
+            mBuiltListHasFullyConcealedElements = false;
+        }
+
         mHeaderProcessor.onUrlFocusChange(hasFocus);
         for (int index = 0; index < mPriorityOrderedSuggestionProcessors.size(); index++) {
             mPriorityOrderedSuggestionProcessors.get(index).onUrlFocusChange(hasFocus);