[TTS] Hide the CS UI when entering airplane mode.

When Contextual Search enters a disabled state it removes notifiers
for showing the UI.  However if the UI is already showing it should
hide it immediately.  This CL adds a call to hide when disabling for
any reason, including network connectivity loss.

BUG=783352

Change-Id: I826d38264cd6c0cb5ca6ece804c2f44c3b0ee924
Reviewed-on: https://chromium-review.googlesource.com/917647Reviewed-by: Theresa <twellington@chromium.org>
Commit-Queue: Donn Denman <donnd@chromium.org>
Cr-Commit-Position: refs/heads/master@{#536738}

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

@@ -241,6 +241,11 @@ public class ContextualSearchTabHelper
                 controller.setSelectionClient(
                         mSelectionClientManager.removeContextualSearchSelectionClient());
             }
+            // Also make sure the UI is hidden.
+            ContextualSearchManager contextualSearchManager = getContextualSearchManager(mTab);
+            if (contextualSearchManager != null) {
+                contextualSearchManager.hideContextualSearch(StateChangeReason.UNKNOWN);
+            }
         }
     }