Convert string16 to base::string16 in content.

content/browser/plugin_loader_posix_unittest.cc

Index: content/browser/plugin_loader_posix_unittest.cc
diff --git a/content/browser/plugin_loader_posix_unittest.cc b/content/browser/plugin_loader_posix_unittest.cc
index 8f907232121487b3a8ce48c923e8658cfd85546e..13620f74dd30064e9798081e81b55f0b4e273868 100644
--- a/content/browser/plugin_loader_posix_unittest.cc
+++ b/content/browser/plugin_loader_posix_unittest.cc
@@ -64,11 +64,11 @@ class PluginLoaderPosixTest : public testing::Test {
  public:
   PluginLoaderPosixTest()
       : plugin1_(ASCIIToUTF16("plugin1"), base::FilePath("/tmp/one.plugin"),
-                 ASCIIToUTF16("1.0"), string16()),
+                 ASCIIToUTF16("1.0"), base::string16()),
         plugin2_(ASCIIToUTF16("plugin2"), base::FilePath("/tmp/two.plugin"),
-                 ASCIIToUTF16("2.0"), string16()),
+                 ASCIIToUTF16("2.0"), base::string16()),
         plugin3_(ASCIIToUTF16("plugin3"), base::FilePath("/tmp/three.plugin"),
-                 ASCIIToUTF16("3.0"), string16()),
+                 ASCIIToUTF16("3.0"), base::string16()),
         file_thread_(BrowserThread::FILE, &message_loop_),
         io_thread_(BrowserThread::IO, &message_loop_),
         plugin_loader_(new MockPluginLoaderPosix) {