Add TestBrowserThreadBundle into RenderViewHostTestHarness. Kill some unnecessary real threads.

content/browser/web_contents/web_contents_delegate_unittest.cc

Index: content/browser/web_contents/web_contents_delegate_unittest.cc
diff --git a/content/browser/web_contents/web_contents_delegate_unittest.cc b/content/browser/web_contents/web_contents_delegate_unittest.cc
index 9c5e0e7a2627892c01b8738a358fade336541881..e5bb6790bc6f34a8598c7a3065e3be52e4a00580 100644
--- a/content/browser/web_contents/web_contents_delegate_unittest.cc
+++ b/content/browser/web_contents/web_contents_delegate_unittest.cc
@@ -7,30 +7,16 @@
 #include "base/message_loop.h"
 #include "content/browser/web_contents/web_contents_impl.h"
 #include "content/browser/renderer_host/test_render_view_host.h"
-#include "content/public/browser/browser_thread.h"
 #include "content/public/browser/web_contents_delegate.h"
 #include "content/public/test/test_browser_context.h"
-#include "content/public/test/test_browser_thread.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 namespace content {
 
 class MockWebContentsDelegate : public WebContentsDelegate {
- public:
-  virtual ~MockWebContentsDelegate() {}
 };
 
 class WebContentsDelegateTest : public RenderViewHostImplTestHarness {
- public:
-  WebContentsDelegateTest()
-      : file_user_blocking_thread_(
-            BrowserThread::FILE_USER_BLOCKING, &message_loop_),
-        io_thread_(BrowserThread::IO, &message_loop_) {
-  }
-
- private:
-  TestBrowserThread file_user_blocking_thread_;
-  TestBrowserThread io_thread_;
 };
 
 TEST_F(WebContentsDelegateTest, UnregisterInDestructor) {