[TTS] Fix flaky second-tap on tap-selection.

When a Tap selection is present, a second tap shows the pins, and
the Bar should keep showing.  However this seems to currently be
flaky.

This CL adds a check when a Tap is recognized to see if we're
already showing a Tap-selection.  We were incorrectly starting
a Tap sequence in response to this second tap but that's not
needed since we'll soon get a message for the Long-press gesture
when the pins show.

BUG=717942

Review-Url: https://codereview.chromium.org/2853393003
Cr-Commit-Position: refs/heads/master@{#469033}

chrome/android/java/src/org/chromium/chrome/browser/contextualsearch/ContextualSearchInternalStateController.java

@@ -293,7 +293,12 @@ class ContextualSearchInternalStateController {
                 reset(StateChangeReason.BASE_PAGE_TAP);
                 break;
             case TAP_RECOGNIZED:
-                transitionTo(InternalState.GATHERING_SURROUNDINGS);
+                if (mPreviousState == InternalState.SHOWING_TAP_SEARCH) {
+                    // This is a second-tap on a Tap-selection.
+                    // We'll soon recognize a Long-press and show the edit pins, so nothing needed.
+                } else {
+                    transitionTo(InternalState.GATHERING_SURROUNDINGS);
+                }
                 break;
             case GATHERING_SURROUNDINGS:
                 // We gather surroundings for both Tap and Long-press in order to notify icing.