Adding browsertest to verify that updating forced-installed extensions is possible.

chrome/browser/policy/cloud/test_request_interceptor.h

Index: chrome/browser/policy/cloud/test_request_interceptor.h
diff --git a/chrome/browser/policy/cloud/test_request_interceptor.h b/chrome/browser/policy/cloud/test_request_interceptor.h
index 4ec5978cab3cf8e64c9fbceeb2ab0209fb460208..7838587fc185371e25a867b1ff1d8bbcce76b366 100644
--- a/chrome/browser/policy/cloud/test_request_interceptor.h
+++ b/chrome/browser/policy/cloud/test_request_interceptor.h
@@ -11,6 +11,10 @@
 #include "base/callback.h"
 #include "chrome/browser/policy/proto/cloud/device_management_backend.pb.h"
 
+namespace base {
+class FilePath;
+}
+
 namespace net {
 class NetworkDelegate;
 class URLRequest;
@@ -56,6 +60,9 @@ class TestRequestInterceptor {
       enterprise_management::DeviceRegisterRequest::Type expected_type,
       bool expect_reregister);
 
+  // Returns a JobCallback that will send the contents of |file_path|.
+  static JobCallback FileJob(const base::FilePath& file_path);
+
  private:
   class Delegate;