User agent freezing experiment: include the major version even if frozen

This is almost entirely from Aaron Tagliaboschi's work at
https://chromium-review.googlesource.com/c/chromium/src/+/2019602

This code also removes the unconditional use of GetFrozenUserAgent in
isolated_prerender_tab_helper.cc which looked like a mistake;
::GetUserAgent uses that when the experiment is on.

Bug: 955620
Change-Id: Id4b719e0b4b1aada85418a889203bb5a85a3e72b
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2079466
Commit-Queue: Maksim Orlovich <morlovich@chromium.org>
Reviewed-by: Avi Drissman <avi@chromium.org>
Reviewed-by: Robert Ogden <robertogden@chromium.org>
Reviewed-by: Yoav Weiss <yoavweiss@chromium.org>
Cr-Commit-Position: refs/heads/master@{#756001}

chrome/browser/chrome_content_browser_client.cc

@@ -1105,8 +1105,8 @@ std::string GetUserAgent() {
 
   if (base::FeatureList::IsEnabled(blink::features::kFreezeUserAgent)) {
     return content::GetFrozenUserAgent(
-               command_line->HasSwitch(switches::kUseMobileUserAgent))
-        .as_string();
+        command_line->HasSwitch(switches::kUseMobileUserAgent),
+        version_info::GetMajorVersionNumber());
   }
 
   std::string product = GetProduct();

chrome/browser/chrome_content_browser_client_unittest.cc

@@ -444,7 +444,9 @@ TEST(ChromeContentBrowserClientTest, UserAgentStringFrozen) {
   {
     ChromeContentBrowserClient content_browser_client;
     std::string buffer = content_browser_client.GetUserAgent();
-    EXPECT_EQ(buffer, content::frozen_user_agent_strings::kAndroid);
+    EXPECT_EQ(buffer, base::StringPrintf(
+                          content::frozen_user_agent_strings::kAndroid,
+                          version_info::GetMajorVersionNumber().c_str()));
   }
 
   // Verify the mobile user agent string is returned when using a mobile user
@@ -454,13 +456,17 @@ TEST(ChromeContentBrowserClientTest, UserAgentStringFrozen) {
   {
     ChromeContentBrowserClient content_browser_client;
     std::string buffer = content_browser_client.GetUserAgent();
-    EXPECT_EQ(buffer, content::frozen_user_agent_strings::kAndroidMobile);
+    EXPECT_EQ(buffer, base::StringPrintf(
+                          content::frozen_user_agent_strings::kAndroidMobile,
+                          version_info::GetMajorVersionNumber().c_str()));
   }
 #else
   {
     ChromeContentBrowserClient content_browser_client;
     std::string buffer = content_browser_client.GetUserAgent();
-    EXPECT_EQ(buffer, content::frozen_user_agent_strings::kDesktop);
+    EXPECT_EQ(buffer, base::StringPrintf(
+                          content::frozen_user_agent_strings::kDesktop,
+                          version_info::GetMajorVersionNumber().c_str()));
   }
 #endif
 }

chrome/browser/prerender/isolated/isolated_prerender_tab_helper.cc

@@ -13,6 +13,7 @@
 #include "base/metrics/histogram_macros.h"
 #include "base/optional.h"
 #include "base/time/time.h"
+#include "chrome/browser/chrome_content_browser_client.h"
 #include "chrome/browser/navigation_predictor/navigation_predictor_keyed_service_factory.h"
 #include "chrome/browser/net/prediction_options.h"
 #include "chrome/browser/prerender/isolated/isolated_prerender_features.h"
@@ -33,7 +34,6 @@
 #include "content/public/browser/storage_partition.h"
 #include "content/public/browser/web_contents.h"
 #include "content/public/common/content_constants.h"
-#include "content/public/common/user_agent.h"
 #include "net/base/load_flags.h"
 #include "net/base/net_errors.h"
 #include "net/base/network_isolation_key.h"
@@ -545,7 +545,7 @@ void IsolatedPrerenderTabHelper::CreateIsolatedURLLoaderFactory() {
       IsolatedPrerenderServiceFactory::GetForProfile(profile_);
 
   auto context_params = network::mojom::NetworkContextParams::New();
-  context_params->user_agent = content::GetFrozenUserAgent(true).as_string();
+  context_params->user_agent = ::GetUserAgent();
   context_params->initial_custom_proxy_config =
       isolated_prerender_service->proxy_configurator()
           ->CreateCustomProxyConfig();

content/common/user_agent.cc

@@ -163,12 +163,16 @@ std::string BuildOSCpuInfo(bool include_android_build_number) {
   return os_cpu;
 }
 
-base::StringPiece GetFrozenUserAgent(bool mobile) {
+std::string GetFrozenUserAgent(bool mobile, std::string major_version) {
+  std::string user_agent;
 #if defined(OS_ANDROID)
-  return mobile ? frozen_user_agent_strings::kAndroidMobile
-                : frozen_user_agent_strings::kAndroid;
+  user_agent = mobile ? frozen_user_agent_strings::kAndroidMobile
+                      : frozen_user_agent_strings::kAndroid;
+#else
+  user_agent = frozen_user_agent_strings::kDesktop;
 #endif
-  return frozen_user_agent_strings::kDesktop;
+
+  return base::StringPrintf(user_agent.c_str(), major_version.c_str());
 }
 
 std::string BuildUserAgentFromProduct(const std::string& product) {

content/public/common/user_agent.h

@@ -18,14 +18,14 @@ namespace frozen_user_agent_strings {
 
 const char kDesktop[] =
     "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, "
-    "like Gecko) Chrome/75.0.3764.0 Safari/537.36";
+    "like Gecko) Chrome/%s.0.0.0 Safari/537.36";
 const char kAndroid[] =
     "Mozilla/5.0 (Linux; Android 9; Unspecified Device) "
-    "AppleWebKit/537.36 (KHTML, like Gecko) Chrome/75.0.3764.0 "
+    "AppleWebKit/537.36 (KHTML, like Gecko) Chrome/%s.0.0.0 "
     "Safari/537.36";
 const char kAndroidMobile[] =
     "Mozilla/5.0 (Linux; Android 9; Unspecified Device) "
-    "AppleWebKit/537.36 (KHTML, like Gecko) Chrome/75.0.3764.0 Mobile "
+    "AppleWebKit/537.36 (KHTML, like Gecko) Chrome/%s.0.0.0 Mobile "
     "Safari/537.36";
 
 }  // namespace frozen_user_agent_strings
@@ -50,7 +50,8 @@ CONTENT_EXPORT std::string GetOSVersion(bool include_android_build_number);
 
 // Returns the frozen User-agent string for
 // https://github.com/WICG/ua-client-hints.
-CONTENT_EXPORT base::StringPiece GetFrozenUserAgent(bool mobile);
+CONTENT_EXPORT std::string GetFrozenUserAgent(bool mobile,
+                                              std::string major_version);
 
 // Helper function to generate a full user agent string from a short
 // product name.

content/shell/browser/shell_content_browser_client.cc

@@ -100,8 +100,8 @@ std::string GetShellUserAgent() {
   base::CommandLine* command_line = base::CommandLine::ForCurrentProcess();
   if (base::FeatureList::IsEnabled(blink::features::kFreezeUserAgent)) {
     return content::GetFrozenUserAgent(
-               command_line->HasSwitch(switches::kUseMobileUserAgent))
-        .as_string();
+        command_line->HasSwitch(switches::kUseMobileUserAgent),
+        CONTENT_SHELL_MAJOR_VERSION);
   }
   if (command_line->HasSwitch(switches::kUseMobileUserAgent))
     product += " Mobile";

third_party/blink/web_tests/http/tests/navigation/frozen-useragent.html

@@ -12,11 +12,12 @@
     var platform = navigator.platform;
 
     // Validate the user agent string using the following frozen user agent strings found in content/common/user_agent.h:
-    var desktopUserAgent = "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/75.0.3764.0 Safari/537.36"
+    // The version is 99 since that's what content_shell uses.
+    var desktopUserAgent = "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/99.0.0.0 Safari/537.36"
     var frozenUserAgents = [
       desktopUserAgent,
-      "Mozilla/5.0 (Linux; Android 9; Unspecified Device) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/75.0.3764.0 Safari/537.36",
-      "Mozilla/5.0 (Linux; Android 9; Unspecified Device) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/75.0.3764.0 Mobile Safari/537.36"
+      "Mozilla/5.0 (Linux; Android 9; Unspecified Device) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/99.0.0.0 Safari/537.36",
+      "Mozilla/5.0 (Linux; Android 9; Unspecified Device) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/99.0.0.0 Mobile Safari/537.36"
     ];
 
     // Platform values should match strings defined in third_party/blink/renderer/core/frame/navigator.cc.