Split BrowserThread into public API and private implementation, step 1.

chrome/browser/prerender/prerender_tracker_unittest.cc

Index: chrome/browser/prerender/prerender_tracker_unittest.cc
diff --git a/chrome/browser/prerender/prerender_tracker_unittest.cc b/chrome/browser/prerender/prerender_tracker_unittest.cc
index f07fd2ba4be19ac782e5d4b861a7eb9fd0181b3c..7399264d67d1d7135abbab8622b7fb312fc0e9a8 100644
--- a/chrome/browser/prerender/prerender_tracker_unittest.cc
+++ b/chrome/browser/prerender/prerender_tracker_unittest.cc
@@ -8,7 +8,7 @@
 #include "chrome/browser/prerender/prerender_manager.h"
 #include "chrome/browser/prerender/prerender_tracker.h"
 #include "chrome/test/base/testing_browser_process.h"
-#include "content/browser/browser_thread.h"
+#include "content/test/test_browser_thread.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 namespace prerender {
@@ -70,8 +70,8 @@ class PrerenderTrackerTest : public testing::Test {
 
  private:
   MessageLoop message_loop_;
-  BrowserThread ui_thread_;
-  BrowserThread io_thread_;
+  content::TestBrowserThread ui_thread_;
+  content::TestBrowserThread io_thread_;
 
   scoped_ptr<TestPrerenderManager> prerender_manager_;
 };