Add client cert support to android_webview

android_webview/java/src/org/chromium/android_webview/AwContentsClient.java

Index: android_webview/java/src/org/chromium/android_webview/AwContentsClient.java
diff --git a/android_webview/java/src/org/chromium/android_webview/AwContentsClient.java b/android_webview/java/src/org/chromium/android_webview/AwContentsClient.java
index 22e7c7dacbfd1c80ddb2d5e572fb0ef2a8a03a2a..fa59347f18dd2c8e5076bd37c4b57a8e928244fd 100644
--- a/android_webview/java/src/org/chromium/android_webview/AwContentsClient.java
+++ b/android_webview/java/src/org/chromium/android_webview/AwContentsClient.java
@@ -21,6 +21,8 @@ import org.chromium.content.browser.ContentViewCore;
 import org.chromium.content.browser.WebContentsObserverAndroid;
 import org.chromium.net.NetError;
 
+import java.security.Principal;
+
 /**
  * Base-class that an AwContents embedder derives from to receive callbacks.
  * This extends ContentViewClient, as in many cases we want to pass-thru ContentViewCore
@@ -165,6 +167,12 @@ public abstract class AwContentsClient {
 
     public abstract void onReceivedSslError(ValueCallback<Boolean> callback, SslError error);
 
+    // TODO(sgurun): Make abstract once this has rolled in downstream.
+    public void onReceivedClientCertRequest(
+            final AwContentsClientBridge.ClientCertificateRequestCallback callback,
+            final String[] keyTypes, final Principal[] principals, final String host,
+            final int port) { }
+
     public abstract void onReceivedLoginRequest(String realm, String account, String args);
 
     public abstract void onFormResubmission(Message dontResend, Message resend);