Tab manager view should hide on press of back key

chrome/android/shell/java/src/org/chromium/chrome/shell/ChromeShellActivity.java

Index: chrome/android/shell/java/src/org/chromium/chrome/shell/ChromeShellActivity.java
diff --git a/chrome/android/shell/java/src/org/chromium/chrome/shell/ChromeShellActivity.java b/chrome/android/shell/java/src/org/chromium/chrome/shell/ChromeShellActivity.java
index 618651d9b9d4bc782daac88f662001498132b467..c8fbd01f1401906ba85e5c6456be917811642484 100644
--- a/chrome/android/shell/java/src/org/chromium/chrome/shell/ChromeShellActivity.java
+++ b/chrome/android/shell/java/src/org/chromium/chrome/shell/ChromeShellActivity.java
@@ -204,13 +204,16 @@ public class ChromeShellActivity extends Activity implements AppMenuPropertiesDe
     @Override
     public boolean onKeyUp(int keyCode, KeyEvent event) {
         if (keyCode == KeyEvent.KEYCODE_BACK) {
+            if (mTabManager.isTabSwitcherVisible()) {
+                mTabManager.hideTabSwitcher();
+                return true;
+            }
             ChromeShellTab tab = getActiveTab();
             if (tab != null && tab.canGoBack()) {
                 tab.goBack();
                 return true;
             }
         }
-
         return super.onKeyUp(keyCode, event);
     }