Start upstreaming accessibility.

content/shell/android/java/src/org/chromium/content_shell/ShellManager.java

Index: content/shell/android/java/src/org/chromium/content_shell/ShellManager.java
diff --git a/content/shell/android/java/src/org/chromium/content_shell/ShellManager.java b/content/shell/android/java/src/org/chromium/content_shell/ShellManager.java
index e97ba20978a0f1e4b40a235b79e27a0d339badbf..3aba276bf6e1efd186202d30ce3301edbcb49762 100644
--- a/content/shell/android/java/src/org/chromium/content_shell/ShellManager.java
+++ b/content/shell/android/java/src/org/chromium/content_shell/ShellManager.java
@@ -86,9 +86,14 @@ public class ShellManager extends FrameLayout {
         shellView.setSurfaceView(mSurfaceView);
 
         removeAllViews();
+        if (mActiveShell != null && mActiveShell.getContentView() != null) {
+            mActiveShell.getContentView().onHide();
+        }
+
         addView(shellView, new FrameLayout.LayoutParams(
                 FrameLayout.LayoutParams.MATCH_PARENT, FrameLayout.LayoutParams.MATCH_PARENT));
         mActiveShell = shellView;
+        if (mActiveShell.getContentView() != null) mActiveShell.getContentView().onShow();
 
         return shellView;
     }