NoStatePrefetch: Add Purpose:prefetch header

The header should be set for all requests originating from
nostate-prefetch, main resource, all redirects and all subresources.

Using base::BindRepeating in new tests because of presubmit
warning, also switched similar tests to it for consistency.

Bug: 796855
Change-Id: I90614fac595f2dbc087a6ac99f54e2fc7d37f89a
Reviewed-on: https://chromium-review.googlesource.com/1104692
Commit-Queue: Egor Pasko <pasko@chromium.org>
Reviewed-by: John Abd-El-Malek <jam@chromium.org>
Reviewed-by: Matthew Cary <mattcary@chromium.org>
Cr-Commit-Position: refs/heads/master@{#568409}

chrome/browser/chrome_content_browser_client.cc

@@ -144,6 +144,7 @@
 #include "chrome/common/pepper_permission_util.h"
 #include "chrome/common/pref_names.h"
 #include "chrome/common/prerender_url_loader_throttle.h"
+#include "chrome/common/prerender_util.h"
 #include "chrome/common/render_messages.h"
 #include "chrome/common/renderer_configuration.mojom.h"
 #include "chrome/common/secure_origin_whitelist.h"
@@ -2152,9 +2153,13 @@ void ChromeContentBrowserClient::NavigationRequestStarted(
           web_contents->GetBrowserContext(), url);
   prerender::PrerenderContents* prerender_contents =
       prerender::PrerenderContents::FromWebContents(web_contents);
-  if (prerender_contents) {
-    if (prerender_contents->prerender_mode() == prerender::PREFETCH_ONLY)
-      *extra_load_flags = net::LOAD_PREFETCH;
+  if (prerender_contents &&
+      prerender_contents->prerender_mode() == prerender::PREFETCH_ONLY) {
+    *extra_load_flags = net::LOAD_PREFETCH;
+    if (*extra_headers == nullptr)
+      *extra_headers = std::make_unique<net::HttpRequestHeaders>();
+    extra_headers->get()->SetHeader(prerender::kPurposeHeaderName,
+                                    prerender::kPurposeHeaderValue);
   }
 }
 

chrome/browser/prerender/prerender_nostate_prefetch_browsertest.cc

@@ -54,6 +54,12 @@ using prerender::test_utils::DestructionWaiter;
 using prerender::test_utils::RequestCounter;
 using prerender::test_utils::TestPrerender;
 
+namespace {
+
+const char kExpectedPurposeHeaderOnPrefetch[] = "Purpose";
+
+}  // namespace
+
 namespace prerender {
 
 const char k302RedirectPage[] = "/prerender/302_redirect.html";
@@ -257,7 +263,7 @@ IN_PROC_BROWSER_TEST_F(NoStatePrefetchBrowserTest, PrefetchLoadFlag) {
   GURL prefetch_page = src_server()->GetURL(kPrefetchPage);
   GURL prefetch_script = src_server()->GetURL(kPrefetchScript);
 
-  content::URLLoaderInterceptor interceptor(base::Bind(
+  content::URLLoaderInterceptor interceptor(base::BindRepeating(
       [](const GURL& prefetch_page, const GURL& prefetch_script,
          content::URLLoaderInterceptor::RequestParams* params) {
         if (params->url_request.url == prefetch_page ||
@@ -277,6 +283,63 @@ IN_PROC_BROWSER_TEST_F(NoStatePrefetchBrowserTest, PrefetchLoadFlag) {
   test_prerender->WaitForLoads(0);
 }
 
+// Check that prefetched resources and subresources set the 'Purpose: prefetch'
+// header.
+IN_PROC_BROWSER_TEST_F(NoStatePrefetchBrowserTest, PurposeHeaderIsSet) {
+  GURL prefetch_page = src_server()->GetURL(kPrefetchPage);
+  GURL prefetch_script = src_server()->GetURL(kPrefetchScript);
+
+  content::URLLoaderInterceptor interceptor(base::BindRepeating(
+      [](const GURL& prefetch_page, const GURL& prefetch_script,
+         content::URLLoaderInterceptor::RequestParams* params) {
+        if (params->url_request.url == prefetch_page ||
+            params->url_request.url == prefetch_script) {
+          EXPECT_TRUE(params->url_request.load_flags & net::LOAD_PREFETCH);
+          EXPECT_TRUE(params->url_request.headers.HasHeader(
+              kExpectedPurposeHeaderOnPrefetch));
+          std::string purpose_header;
+          params->url_request.headers.GetHeader(
+              kExpectedPurposeHeaderOnPrefetch, &purpose_header);
+          EXPECT_EQ("prefetch", purpose_header);
+        }
+        return false;
+      },
+      prefetch_page, prefetch_script));
+
+  std::unique_ptr<TestPrerender> test_prerender =
+      PrefetchFromFile(kPrefetchPage, FINAL_STATUS_NOSTATE_PREFETCH_FINISHED);
+  WaitForRequestCount(prefetch_page, 1);
+  WaitForRequestCount(prefetch_script, 1);
+}
+
+// Check that on normal navigations the 'Purpose: prefetch' header is not set.
+IN_PROC_BROWSER_TEST_F(NoStatePrefetchBrowserTest,
+                       PurposeHeaderNotSetWhenNotPrefetching) {
+  GURL prefetch_page = src_server()->GetURL(kPrefetchPage);
+  GURL prefetch_script = src_server()->GetURL(kPrefetchScript);
+  GURL prefetch_script2 = src_server()->GetURL(kPrefetchScript2);
+
+  content::URLLoaderInterceptor interceptor(base::BindRepeating(
+      [](const GURL& prefetch_page, const GURL& prefetch_script,
+         const GURL& prefetch_script2,
+         content::URLLoaderInterceptor::RequestParams* params) {
+        if (params->url_request.url == prefetch_page ||
+            params->url_request.url == prefetch_script ||
+            params->url_request.url == prefetch_script2) {
+          EXPECT_FALSE(params->url_request.load_flags & net::LOAD_PREFETCH);
+          EXPECT_FALSE(params->url_request.headers.HasHeader(
+              kExpectedPurposeHeaderOnPrefetch));
+        }
+        return false;
+      },
+      prefetch_page, prefetch_script, prefetch_script2));
+
+  ui_test_utils::NavigateToURL(current_browser(), prefetch_page);
+  WaitForRequestCount(prefetch_page, 1);
+  WaitForRequestCount(prefetch_script, 1);
+  WaitForRequestCount(prefetch_script2, 1);
+}
+
 // Check that a prefetch followed by a load produces the approriate
 // histograms. Note that other histogram testing is done in
 // browser/page_load_metrics, in particular, testing the combinations of
@@ -411,11 +474,7 @@ IN_PROC_BROWSER_TEST_F(NoStatePrefetchBrowserTest, Prefetch301LoadFlags) {
       "/server-redirect/?" + net::EscapeQueryParamValue(kPrefetchPage, false);
   GURL redirect_url = src_server()->GetURL(redirect_path);
   GURL page_url = src_server()->GetURL(kPrefetchPage);
-  auto verify_prefetch_only = base::Bind([](net::URLRequest* request) {
-    EXPECT_TRUE(request->load_flags() & net::LOAD_PREFETCH);
-  });
-
-  content::URLLoaderInterceptor interceptor(base::Bind(
+  content::URLLoaderInterceptor interceptor(base::BindRepeating(
       [](const GURL& page_url,
          content::URLLoaderInterceptor::RequestParams* params) {
         if (params->url_request.url == page_url)

chrome/common/prerender_url_loader_throttle.cc

@@ -131,6 +131,7 @@ void PrerenderURLLoaderThrottle::WillStartRequest(
 #endif  // OS_ANDROID
 
   if (mode_ == PREFETCH_ONLY) {
+    request->headers.SetHeader(kPurposeHeaderName, kPurposeHeaderValue);
     detached_timer_.Start(FROM_HERE,
                           base::TimeDelta::FromMilliseconds(
                               content::kDefaultDetachableCancelDelayMs),

chrome/common/prerender_util.cc

@@ -46,6 +46,8 @@ int GetResourceType(bool is_main_resource, bool is_redirect, bool is_no_store) {
 }  // namespace
 
 const char kFollowOnlyWhenPrerenderShown[] = "follow-only-when-prerender-shown";
+const char kPurposeHeaderName[] = "Purpose";
+const char kPurposeHeaderValue[] = "prefetch";
 
 bool DoesURLHaveValidScheme(const GURL& url) {
   return (url.SchemeIsHTTPOrHTTPS() ||

chrome/common/prerender_util.h

@@ -13,6 +13,8 @@ class GURL;
 
 namespace prerender {
 extern const char kFollowOnlyWhenPrerenderShown[];
+extern const char kPurposeHeaderName[];
+extern const char kPurposeHeaderValue[];
 
 // Returns true iff the scheme of the URL given is valid for prerendering.
 bool DoesURLHaveValidScheme(const GURL& url);