Add command line flags to enable greasing HTTP/2.

Multiple server developers approached me either in private or on the
IETF mailing list asking for a way to test this feature.

Bug: 1020233
Change-Id: Ibba5831e8153090b0dde81aa2519dfc75d4f362a
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1894305
Commit-Queue: Ryan Hamilton <rch@chromium.org>
Auto-Submit: Bence Béky <bnc@chromium.org>
Reviewed-by: Ryan Hamilton <rch@chromium.org>
Cr-Commit-Position: refs/heads/master@{#712194}

components/network_session_configurator/browser/network_session_configurator.cc

@@ -135,8 +135,9 @@ void ConfigureHttp2Params(const base::CommandLine& command_line,
   // identifier to "grease" settings, see
   // https://tools.ietf.org/html/draft-bishop-httpbis-grease-00.
   params->http2_settings = GetHttp2Settings(http2_trial_params);
-  if (GetVariationParam(http2_trial_params, "http2_grease_settings") ==
-      "true") {
+  if (command_line.HasSwitch(switches::kHttp2GreaseSettings) ||
+      GetVariationParam(http2_trial_params, "http2_grease_settings") ==
+          "true") {
     spdy::SpdySettingsId id = 0x0a0a + 0x1000 * base::RandGenerator(0xf + 1) +
                               0x0010 * base::RandGenerator(0xf + 1);
     uint32_t value = base::RandGenerator(
@@ -146,8 +147,9 @@ void ConfigureHttp2Params(const base::CommandLine& command_line,
 
   // Optionally define a frame of reserved type to "grease" frame types, see
   // https://tools.ietf.org/html/draft-bishop-httpbis-grease-00.
-  if (GetVariationParam(http2_trial_params, "http2_grease_frame_type") ==
-      "true") {
+  if (command_line.HasSwitch(switches::kHttp2GreaseFrameType) ||
+      GetVariationParam(http2_trial_params, "http2_grease_frame_type") ==
+          "true") {
     const uint8_t type = 0x0b + 0x1f * base::RandGenerator(8);
     const uint8_t flags =
         base::RandGenerator(std::numeric_limits<uint8_t>::max() + 1);

components/network_session_configurator/browser/network_session_configurator_unittest.cc

@@ -817,7 +817,23 @@ TEST_F(NetworkSessionConfiguratorTest, QuicHeadersIncludeH2StreamDependency) {
   EXPECT_TRUE(params_.quic_params.headers_include_h2_stream_dependency);
 }
 
-TEST_F(NetworkSessionConfiguratorTest, Http2GreaseSettings) {
+TEST_F(NetworkSessionConfiguratorTest, Http2GreaseSettingsFromCommandLine) {
+  base::CommandLine command_line(base::CommandLine::NO_PROGRAM);
+  command_line.AppendSwitch(switches::kHttp2GreaseSettings);
+
+  ParseCommandLineAndFieldTrials(command_line);
+
+  bool greased_setting_found = false;
+  for (const auto& setting : params_.http2_settings) {
+    if ((setting.first & 0x0f0f) == 0x0a0a) {
+      greased_setting_found = true;
+      break;
+    }
+  }
+  EXPECT_TRUE(greased_setting_found);
+}
+
+TEST_F(NetworkSessionConfiguratorTest, Http2GreaseSettingsFromFieldTrial) {
   std::map<std::string, std::string> field_trial_params;
   field_trial_params["http2_grease_settings"] = "true";
   variations::AssociateVariationParams("HTTP2", "Enabled", field_trial_params);
@@ -835,7 +851,18 @@ TEST_F(NetworkSessionConfiguratorTest, Http2GreaseSettings) {
   EXPECT_TRUE(greased_setting_found);
 }
 
-TEST_F(NetworkSessionConfiguratorTest, Http2GreaseFrameType) {
+TEST_F(NetworkSessionConfiguratorTest, Http2GreaseFrameTypeFromCommandLine) {
+  base::CommandLine command_line(base::CommandLine::NO_PROGRAM);
+  command_line.AppendSwitch(switches::kHttp2GreaseFrameType);
+
+  ParseCommandLineAndFieldTrials(command_line);
+
+  ASSERT_TRUE(params_.greased_http2_frame);
+  const uint8_t frame_type = params_.greased_http2_frame.value().type;
+  EXPECT_EQ(0x0b, frame_type % 0x1f);
+}
+
+TEST_F(NetworkSessionConfiguratorTest, Http2GreaseFrameTypeFromFieldTrial) {
   std::map<std::string, std::string> field_trial_params;
   field_trial_params["http2_grease_frame_type"] = "true";
   variations::AssociateVariationParams("HTTP2", "Enabled", field_trial_params);

components/network_session_configurator/common/network_switch_list.h

@@ -61,3 +61,9 @@ NETWORK_SWITCH(kTestingFixedHttpsPort, "testing-fixed-https-port")
 // TODO(mmenke): Can we just remove this?  host-resolver-rules is more generally
 // useful.
 NETWORK_SWITCH(kHostRules, "host-rules")
+
+// Enable "greasing" HTTP/2, that is, sending SETTINGS parameters with reserved
+// identifiers and sending frames of reserved types, respectively.  See
+// https://tools.ietf.org/html/draft-bishop-httpbis-grease-00 for more detail.
+NETWORK_SWITCH(kHttp2GreaseSettings, "http2-grease-settings")
+NETWORK_SWITCH(kHttp2GreaseFrameType, "http2-grease-frame-type")