[Android] Suppress tap sound on empty keyboard accessory bar

This fixes on of the funniest bugs so far: when tapping the empty bar of
the keyboar accessory, a tap sound would be emitted. Tapping multiple
times or sliding would be interpreted as multiple quick taps and emit a
weird buzzing noise.
By suppressing the sound effect, the element is still tappable for
accessibility purposes but the sound isn't audible anymore. This only
affects the empty space in the bar - the key icon or other buttons are
still emitting the tap sound to confirm a successful interaction.

Bug: 895767
Change-Id: I4477417edc99324420f88b7a688afe21eee1e9fb
Reviewed-on: https://chromium-review.googlesource.com/c/1288534Reviewed-by: Ioana Pandele <ioanap@chromium.org>
Commit-Queue: Friedrich Horschig [CEST] <fhorschig@chromium.org>
Cr-Commit-Position: refs/heads/master@{#600723}

chrome/android/java/src/org/chromium/chrome/browser/autofill/keyboard_accessory/KeyboardAccessoryView.java

@@ -72,6 +72,7 @@ class KeyboardAccessoryView extends LinearLayout {
         });
         setOnClickListener(view -> {});
         setClickable(false); // Disables the "Double-tap to activate" Talkback reading.
+        setSoundEffectsEnabled(false);
     }
 
     void setVisible(boolean visible) {