Add command line overrides for GCM checkin URL & MCS endpoint

It can be useful during development to have Chrome connect to test GCM
environments instead of production GCM.

BUG=https://b.corp.google.com/23523760

Review URL: https://codereview.chromium.org/1492913002

Cr-Commit-Position: refs/heads/master@{#362965}

components/gcm_driver/gcm_client_impl.cc

@@ -478,7 +478,9 @@ void GCMClientImpl::StartGCM() {
 void GCMClientImpl::InitializeMCSClient() {
   std::vector<GURL> endpoints;
   endpoints.push_back(gservices_settings_.GetMCSMainEndpoint());
-  endpoints.push_back(gservices_settings_.GetMCSFallbackEndpoint());
+  GURL fallback_endpoint = gservices_settings_.GetMCSFallbackEndpoint();
+  if (fallback_endpoint.is_valid())
+    endpoints.push_back(fallback_endpoint);
   connection_factory_ = internals_builder_->BuildConnectionFactory(
       endpoints,
       GetGCMBackoffPolicy(),

google_apis/gcm/engine/gservices_settings.cc

@@ -177,11 +177,6 @@ const base::TimeDelta GServicesSettings::MinimumCheckinInterval() {
   return base::TimeDelta::FromSeconds(kMinimumCheckinInterval);
 }
 
-// static
-const GURL GServicesSettings::DefaultCheckinURL() {
-  return GURL(kDefaultCheckinURL);
-}
-
 // static
 std::string GServicesSettings::CalculateDigest(const SettingsMap& settings) {
   unsigned char hash[base::kSHA1Length];
@@ -283,6 +278,10 @@ base::TimeDelta GServicesSettings::GetCheckinInterval() const {
 }
 
 GURL GServicesSettings::GetCheckinURL() const {
+  base::CommandLine* command_line = base::CommandLine::ForCurrentProcess();
+  if (command_line->HasSwitch(switches::kGCMCheckinURL))
+    return GURL(command_line->GetSwitchValueASCII(switches::kGCMCheckinURL));
+
   SettingsMap::const_iterator iter = settings_.find(kCheckinURLKey);
   if (iter == settings_.end() || iter->second.empty())
     return GURL(kDefaultCheckinURL);
@@ -290,6 +289,10 @@ GURL GServicesSettings::GetCheckinURL() const {
 }
 
 GURL GServicesSettings::GetMCSMainEndpoint() const {
+  base::CommandLine* command_line = base::CommandLine::ForCurrentProcess();
+  if (command_line->HasSwitch(switches::kGCMMCSEndpoint))
+    return GURL(command_line->GetSwitchValueASCII(switches::kGCMMCSEndpoint));
+
   // Get alternative hostname or use default.
   std::string mcs_hostname;
   SettingsMap::const_iterator iter = settings_.find(kMCSHostnameKey);
@@ -316,6 +319,10 @@ GURL GServicesSettings::GetMCSMainEndpoint() const {
 }
 
 GURL GServicesSettings::GetMCSFallbackEndpoint() const {
+  base::CommandLine* command_line = base::CommandLine::ForCurrentProcess();
+  if (command_line->HasSwitch(switches::kGCMMCSEndpoint))
+    return GURL();  // No fallback endpoint when using command line override.
+
   // Get alternative hostname or use default.
   std::string mcs_hostname;
   SettingsMap::const_iterator iter = settings_.find(kMCSHostnameKey);
@@ -335,15 +342,15 @@ GURL GServicesSettings::GetMCSFallbackEndpoint() const {
 }
 
 GURL GServicesSettings::GetRegistrationURL() const {
-  SettingsMap::const_iterator iter = settings_.find(kRegistrationURLKey);
-  if (iter == settings_.end() || iter->second.empty()) {
-    base::CommandLine* command_line = base::CommandLine::ForCurrentProcess();
-    if (!command_line->HasSwitch(switches::kGCMRegistrationURL))
-      return GURL(kDefaultRegistrationURL);
-
+  base::CommandLine* command_line = base::CommandLine::ForCurrentProcess();
+  if (command_line->HasSwitch(switches::kGCMRegistrationURL)) {
     return GURL(
         command_line->GetSwitchValueASCII(switches::kGCMRegistrationURL));
   }
+
+  SettingsMap::const_iterator iter = settings_.find(kRegistrationURLKey);
+  if (iter == settings_.end() || iter->second.empty())
+    return GURL(kDefaultRegistrationURL);
   return GURL(iter->second);
 }
 

google_apis/gcm/engine/gservices_settings.h

@@ -26,9 +26,6 @@ class GCM_EXPORT GServicesSettings {
   // Minimum periodic checkin interval in seconds.
   static const base::TimeDelta MinimumCheckinInterval();
 
-  // Default checkin URL.
-  static const GURL DefaultCheckinURL();
-
   // Calculates digest of provided settings.
   static std::string CalculateDigest(const SettingsMap& settings);
 
@@ -56,7 +53,7 @@ class GCM_EXPORT GServicesSettings {
   // Gets address of main MCS endpoint.
   GURL GetMCSMainEndpoint() const;
 
-  // Gets address of fallback MCS endpoint.
+  // Gets address of fallback MCS endpoint. Will be empty if there isn't one.
   GURL GetMCSFallbackEndpoint() const;
 
   // Gets the URL to use when registering or unregistering the apps.

google_apis/gcm/engine/gservices_switches.cc

@@ -6,6 +6,14 @@
 
 namespace switches {
 
+// Sets the checkin service endpoint that will be used for performing Google
+// Cloud Messaging checkins.
+const char kGCMCheckinURL[] = "gcm-checkin-url";
+
+// Sets the Mobile Connection Server endpoint that will be used for Google
+// Cloud Messaging.
+const char kGCMMCSEndpoint[] = "gcm-mcs-endpoint";
+
 // Sets the registration endpoint that will be used for creating new Google
 // Cloud Messaging registrations.
 const char kGCMRegistrationURL[] = "gcm-registration-url";

google_apis/gcm/engine/gservices_switches.h

@@ -7,6 +7,8 @@
 
 namespace switches {
 
+extern const char kGCMCheckinURL[];
+extern const char kGCMMCSEndpoint[];
 extern const char kGCMRegistrationURL[];
 
 }  // namespace switches

google_apis/gcm/tools/mcs_probe.cc

@@ -449,7 +449,7 @@ void MCSProbe::CheckIn() {
                                            chrome_build_proto);
 
   checkin_request_.reset(new CheckinRequest(
-      GServicesSettings::DefaultCheckinURL(),
+      GServicesSettings().GetCheckinURL(),
       request_info,
       kDefaultBackoffPolicy,
       base::Bind(&MCSProbe::OnCheckInCompleted, base::Unretained(this)),