Abstract WebContentsObserver from Autofill shared code

components/autofill/browser/test_autofill_driver.cc

Index: components/autofill/browser/test_autofill_driver.cc
diff --git a/components/autofill/browser/test_autofill_driver.cc b/components/autofill/browser/test_autofill_driver.cc
new file mode 100644
index 0000000000000000000000000000000000000000..3fb24eaba32a5ea4db024db0e5bbe94adc1d5f43
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+++ b/components/autofill/browser/test_autofill_driver.cc
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+// Copyright 2013 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "components/autofill/browser/test_autofill_driver.h"
+
+namespace autofill {
+
+TestAutofillDriver::TestAutofillDriver(content::WebContents* web_contents)
+    : content::WebContentsObserver(web_contents) {}
+
+TestAutofillDriver::~TestAutofillDriver() {}
+
+content::WebContents* TestAutofillDriver::GetWebContents() {
+  return web_contents();
+}
+
+}  // namespace autofill