Make the TestServer use an absolute document root path.

content/browser/site_per_process_browsertest.cc

Index: content/browser/site_per_process_browsertest.cc
diff --git a/content/browser/site_per_process_browsertest.cc b/content/browser/site_per_process_browsertest.cc
index 99ce0c94b5db4d2b2d09bf2cf2f9f45a47f93da4..4f4b48630c14bc235a0e8d1efb102f914531dbdf 100644
--- a/content/browser/site_per_process_browsertest.cc
+++ b/content/browser/site_per_process_browsertest.cc
@@ -169,7 +169,8 @@ IN_PROC_BROWSER_TEST_F(SitePerProcessBrowserTest, DISABLED_CrossSiteIframe) {
   net::TestServer https_server(
       net::TestServer::TYPE_HTTPS,
       net::TestServer::kLocalhost,
-      base::FilePath(FILE_PATH_LITERAL("content/test/data")));
+      net::TestServer::GetSourceRelativePath(
+          base::FilePath(FILE_PATH_LITERAL("content/test/data"))));
   ASSERT_TRUE(https_server.Start());
   GURL main_url(test_server()->GetURL("files/site_per_process_main.html"));
 
@@ -201,7 +202,8 @@ IN_PROC_BROWSER_TEST_F(SitePerProcessBrowserTest,
   net::TestServer https_server(
       net::TestServer::TYPE_HTTPS,
       net::TestServer::kLocalhost,
-      base::FilePath(FILE_PATH_LITERAL("content/test/data")));
+      net::TestServer::GetSourceRelativePath(
+          base::FilePath(FILE_PATH_LITERAL("content/test/data"))));
   ASSERT_TRUE(https_server.Start());
 
   GURL main_url(test_server()->GetURL("files/site_per_process_main.html"));
@@ -325,7 +327,8 @@ IN_PROC_BROWSER_TEST_F(SitePerProcessBrowserTest,
   net::TestServer https_server(
       net::TestServer::TYPE_HTTPS,
       net::TestServer::kLocalhost,
-      base::FilePath(FILE_PATH_LITERAL("content/test/data")));
+      net::TestServer::GetSourceRelativePath(
+          base::FilePath(FILE_PATH_LITERAL("content/test/data"))));
   ASSERT_TRUE(https_server.Start());
 
   GURL main_url(test_server()->GetURL("files/site_per_process_main.html"));