[android_webview] Fix UAF in request interception code.

android_webview/native/android_protocol_handler.cc

Index: android_webview/native/android_protocol_handler.cc
diff --git a/android_webview/native/android_protocol_handler.cc b/android_webview/native/android_protocol_handler.cc
index 407f62f1dffea489bc937a3d370deb8246cba021..74b449c2de3aed40a08ae15608cd0fa0fca3f901 100644
--- a/android_webview/native/android_protocol_handler.cc
+++ b/android_webview/native/android_protocol_handler.cc
@@ -60,6 +60,8 @@ class AndroidStreamReaderURLRequestJobDelegateImpl
  public:
   AndroidStreamReaderURLRequestJobDelegateImpl();
 
+  virtual void OnStart() OVERRIDE;
+
   virtual scoped_ptr<InputStream> OpenInputStream(
       JNIEnv* env,
       const GURL& url) OVERRIDE;
@@ -131,6 +133,10 @@ AndroidStreamReaderURLRequestJobDelegateImpl::
 ~AndroidStreamReaderURLRequestJobDelegateImpl() {
 }
 
+void AndroidStreamReaderURLRequestJobDelegateImpl::OnStart() {
+  // noop.
+}
+
 scoped_ptr<InputStream>
 AndroidStreamReaderURLRequestJobDelegateImpl::OpenInputStream(
     JNIEnv* env, const GURL& url) {