[fuchsia] Allow system config to request Android-ish user agent OS.

Allow WebEngine to be configured to report an Android-like UserAgent
via the system-provided config-data, to allow it to be fetch the right
form of content for the device form-factor.

This will likely be replaced with options to configure the Client Hints
reported, on a per-instance basis, once those are standardized.

Bug: b/171582703, 1010256
Change-Id: I9db408be09ec9b9a78facc7b078d635b96c3637b
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2522071
Commit-Queue: Wez <wez@chromium.org>
Commit-Queue: John Abd-El-Malek <jam@chromium.org>
Reviewed-by: John Abd-El-Malek <jam@chromium.org>
Auto-Submit: Wez <wez@chromium.org>
Cr-Commit-Position: refs/heads/master@{#825042}

content/common/user_agent.cc

@@ -6,7 +6,6 @@
 
 #include <stdint.h>
 
-#include "base/feature_list.h"
 #include "base/strings/strcat.h"
 #include "base/strings/string_util.h"
 #include "base/strings/stringprintf.h"

fuchsia/engine/browser/web_engine_content_browser_client.cc

@@ -8,6 +8,7 @@
 #include <string>
 #include <utility>
 
+#include "base/command_line.h"
 #include "base/stl_util.h"
 #include "base/strings/string_split.h"
 #include "components/version_info/version_info.h"
@@ -99,13 +100,22 @@ std::string WebEngineContentBrowserClient::GetProduct() {
 }
 
 std::string WebEngineContentBrowserClient::GetUserAgent() {
-  std::string user_agent = content::BuildUserAgentFromProduct(GetProduct());
+  std::string user_agent;
+  if (base::CommandLine::ForCurrentProcess()->HasSwitch(
+          switches::kUseLegacyAndroidUserAgent)) {
+    user_agent =
+        content::BuildUserAgentFromOSAndProduct("Linux; Android", GetProduct());
+  } else {
+    user_agent = content::BuildUserAgentFromProduct(GetProduct());
+  }
+
   if (base::CommandLine::ForCurrentProcess()->HasSwitch(
           switches::kUserAgentProductAndVersion)) {
     user_agent +=
         " " + base::CommandLine::ForCurrentProcess()->GetSwitchValueNative(
                   switches::kUserAgentProductAndVersion);
   }
+
   return user_agent;
 }
 

fuchsia/engine/context_provider_impl.cc

@@ -168,6 +168,7 @@ bool MaybeAddCommandLineArgsFromConfig(const base::Value& config,
       switches::kForceMaxTextureSize,
       switches::kMaxDecodedImageSizeMb,
       switches::kRendererProcessLimit,
+      switches::kUseLegacyAndroidUserAgent,
       switches::kWebglAntialiasingMode,
       switches::kWebglMSAASampleCount,
   };

fuchsia/engine/switches.cc

@@ -18,5 +18,6 @@ const char kUseLegacyMetricsService[] = "use-legacy-metrics-service";
 const char kCorsExemptHeaders[] = "cors-exempt-headers";
 const char kEnableCastStreamingReceiver[] = "enable-cast-streaming-receiver";
 const char kCdmDataDirectory[] = "cdm-data-directory";
+const char kUseLegacyAndroidUserAgent[] = "use-legacy-android-user-agent";
 
 }  // namespace switches

fuchsia/engine/switches.h

@@ -53,6 +53,9 @@ extern const char kEnableCastStreamingReceiver[];
 // Data directory to be used for CDM user data.
 extern const char kCdmDataDirectory[];
 
+// Enables reporting of an Android-like User Agent string.
+extern const char kUseLegacyAndroidUserAgent[];
+
 }  // namespace switches
 
 #endif  // FUCHSIA_ENGINE_SWITCHES_H_

fuchsia/engine/web_engine_integration_test.cc

@@ -71,7 +71,7 @@ class WebEngineIntegrationMediaTest : public WebEngineIntegrationTest {
   std::unique_ptr<media::FakeAudioConsumerService> fake_audio_consumer_service_;
 };
 
-class WebEngineIntegrationUserAgentTest : public WebEngineIntegrationTest {
+class WebEngineIntegrationUserAgentTest : public WebEngineIntegrationTestBase {
  protected:
   GURL GetEchoUserAgentUrl() {
     static std::string echo_user_agent_header_path =
@@ -81,6 +81,8 @@ class WebEngineIntegrationUserAgentTest : public WebEngineIntegrationTest {
 };
 
 TEST_F(WebEngineIntegrationUserAgentTest, ValidProductOnly) {
+  StartWebEngine(base::CommandLine(base::CommandLine::NO_PROGRAM));
+
   // Create a Context with just an embedder product specified.
   fuchsia::web::CreateContextParams create_params = DefaultContextParams();
   create_params.set_user_agent_product(kValidUserAgentProduct);
@@ -93,12 +95,19 @@ TEST_F(WebEngineIntegrationUserAgentTest, ValidProductOnly) {
       ExecuteJavaScriptWithStringResult("document.body.innerText;");
   EXPECT_TRUE(result.find(kValidUserAgentProduct) != std::string::npos);
 
+  // The UserAgent header should also include the desktop-ish Fuchsia
+  // platform & OS information, by default.
+  constexpr char kFuchsiaUserAgentContents[] = "(X11; Fuchsia)";
+  EXPECT_TRUE(result.find(kFuchsiaUserAgentContents) != std::string::npos);
+
   // Query & verify that the navigator.userAgent contains the product tag.
   result = ExecuteJavaScriptWithStringResult("navigator.userAgent;");
   EXPECT_TRUE(result.find(kValidUserAgentProduct) != std::string::npos);
 }
 
 TEST_F(WebEngineIntegrationUserAgentTest, ValidProductAndVersion) {
+  StartWebEngine(base::CommandLine(base::CommandLine::NO_PROGRAM));
+
   // Create a Context with both product and version specified.
   fuchsia::web::CreateContextParams create_params = DefaultContextParams();
   create_params.set_user_agent_product(kValidUserAgentProduct);
@@ -120,6 +129,8 @@ TEST_F(WebEngineIntegrationUserAgentTest, ValidProductAndVersion) {
 }
 
 TEST_F(WebEngineIntegrationUserAgentTest, InvalidProduct) {
+  StartWebEngine(base::CommandLine(base::CommandLine::NO_PROGRAM));
+
   // Try to create a Context with an invalid embedder product tag.
   fuchsia::web::CreateContextParams create_params = DefaultContextParams();
   create_params.set_user_agent_product(kInvalidUserAgentProduct);
@@ -127,6 +138,8 @@ TEST_F(WebEngineIntegrationUserAgentTest, InvalidProduct) {
 }
 
 TEST_F(WebEngineIntegrationUserAgentTest, VersionOnly) {
+  StartWebEngine(base::CommandLine(base::CommandLine::NO_PROGRAM));
+
   // Try to create a Context with an embedder version but no product.
   fuchsia::web::CreateContextParams create_params = DefaultContextParams();
   create_params.set_user_agent_version(kValidUserAgentVersion);
@@ -134,6 +147,8 @@ TEST_F(WebEngineIntegrationUserAgentTest, VersionOnly) {
 }
 
 TEST_F(WebEngineIntegrationUserAgentTest, ValidProductAndInvalidVersion) {
+  StartWebEngine(base::CommandLine(base::CommandLine::NO_PROGRAM));
+
   // Try to create a Context with valid product tag, but invalid version.
   fuchsia::web::CreateContextParams create_params = DefaultContextParams();
   create_params.set_user_agent_product(kValidUserAgentProduct);
@@ -141,6 +156,25 @@ TEST_F(WebEngineIntegrationUserAgentTest, ValidProductAndInvalidVersion) {
   CreateContextAndExpectError(std::move(create_params), ZX_ERR_INVALID_ARGS);
 }
 
+TEST_F(WebEngineIntegrationUserAgentTest, UseLegacyAndroidUserAgent) {
+  base::CommandLine command_line(base::CommandLine::NO_PROGRAM);
+  command_line.AppendSwitch("use-legacy-android-user-agent");
+  StartWebEngine(std::move(command_line));
+
+  // Create a Context with both product and version specified.
+  fuchsia::web::CreateContextParams create_params = DefaultContextParams();
+  CreateContextAndFrameAndLoadUrl(std::move(create_params),
+                                  GetEchoUserAgentUrl());
+
+  // Query & verify that the UserAgent header echoed into the document body
+  // contains the legacy Android data.
+  constexpr char kLegacyAndroidUserAgentContents[] = "(Linux; Android)";
+  std::string result =
+      ExecuteJavaScriptWithStringResult("document.body.innerText;");
+  EXPECT_TRUE(result.find(kLegacyAndroidUserAgentContents) !=
+              std::string::npos);
+}
+
 // Check that if the CreateContextParams has |remote_debugging_port| set then:
 // - DevTools becomes available when the first debuggable Frame is created.
 // - DevTools closes when the last debuggable Frame is closed.