Fix captive portal can't show certificate problem

Captive portal overrides two shouldOverrideUrlLoading methods,
but show certificate logic only be implemented in deprecated one.

Bug: 133714666
Test: -build, flash, boot
      -atest FramworksNetTests
      -manual test

Change-Id: I2656bb709cb0bf259279ca75ad8411cd8c92fb43
Merged-In: I64b05adcb46baf3fca116dbdc5177bc31c71e06d
(cherry picked from commit 9161b5e845)

packages/CaptivePortalLogin/src/com/android/captiveportallogin/CaptivePortalLoginActivity.java

@@ -485,7 +485,10 @@ public class CaptivePortalLoginActivity extends Activity {
             if (request.isForMainFrame()) {
                 mMainFrameUrl = request.getUrl().toString();
             }
-            return false;
+            // Be careful that two shouldOverrideUrlLoading methods are overridden, but
+            // shouldOverrideUrlLoading(WebView view, String url) was deprecated in API level 24.
+            // TODO: delete deprecated one ??
+            return shouldOverrideUrlLoading(view, mMainFrameUrl);
         }
 
         // A web page consisting of a large broken lock icon to indicate SSL failure.