Add FilePath to base namespace.

This updates headers that forward-declare it and a few random places to use the namespace explicitly. There us a using declaration in file_path.h that makes the rest compile, which we can do in future passes.
Review URL: https://codereview.chromium.org/12163003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@180245 0039d316-1c4b-4281-b951-d872f2087c98
diff --git a/net/base/cert_test_util.h b/net/base/cert_test_util.h
index 9f23b7d..db49e87 100644
--- a/net/base/cert_test_util.h
+++ b/net/base/cert_test_util.h
@@ -11,13 +11,15 @@
 #include "net/base/x509_cert_types.h"
 #include "net/base/x509_certificate.h"
 
+namespace base {
 class FilePath;
+}
 
 namespace net {
 
 class EVRootCAMetadata;
 
-CertificateList CreateCertificateListFromFile(const FilePath& certs_dir,
+CertificateList CreateCertificateListFromFile(const base::FilePath& certs_dir,
                                               const std::string& cert_file,
                                               int format);
 
@@ -26,7 +28,7 @@
 // |certs_dir| represents the test certificates directory. |cert_file| is the
 // name of the certificate file. If cert_file contains multiple certificates,
 // the first certificate found will be returned.
-scoped_refptr<X509Certificate> ImportCertFromFile(const FilePath& certs_dir,
+scoped_refptr<X509Certificate> ImportCertFromFile(const base::FilePath& certs_dir,
                                                   const std::string& cert_file);
 
 // ScopedTestEVPolicy causes certificates marked with |policy|, issued from a