Fix back button does not disconnect remoting session

remoting/android/java/src/org/chromium/chromoting/Desktop.java

Index: remoting/android/java/src/org/chromium/chromoting/Desktop.java
diff --git a/remoting/android/java/src/org/chromium/chromoting/Desktop.java b/remoting/android/java/src/org/chromium/chromoting/Desktop.java
index 8868d5ad954951f20b9b85757b747c7f238299fd..d301c092e2e80229faa42473e1fd7b1018e0333c 100644
--- a/remoting/android/java/src/org/chromium/chromoting/Desktop.java
+++ b/remoting/android/java/src/org/chromium/chromoting/Desktop.java
@@ -183,6 +183,13 @@ public class Desktop extends Activity implements View.OnSystemUiVisibilityChange
      */
     @Override
     public boolean dispatchKeyEvent(KeyEvent event) {
+        int keyCode = event.getKeyCode();
+
+        // Dispatch the back button to the system to handle navigation
+        if (keyCode == KeyEvent.KEYCODE_BACK) {
+            return super.dispatchKeyEvent(event);
+        }
+
         // Send TextEvent in two cases:
         //   1. This is an ACTION_MULTIPLE event.
         //   2. The event was generated by on-screen keyboard and Ctrl, Alt and
@@ -192,10 +199,9 @@ public class Desktop extends Activity implements View.OnSystemUiVisibilityChange
         // acts as if it is connected to the remote host.
         if (event.getAction() == KeyEvent.ACTION_MULTIPLE) {
             JniInterface.sendTextEvent(event.getCharacters());
-            return super.dispatchKeyEvent(event);
+            return true;
         }
 
-        int keyCode = event.getKeyCode();
         boolean pressed = event.getAction() == KeyEvent.ACTION_DOWN;
 
         // For Enter getUnicodeChar() returns 10 (line feed), but we still