Use mash::session::mojom::kServiceName instead of a hardcoded string

chrome/test/base/mash_browser_tests_main.cc is the only place where
the hardcoded string "mash_session" is used. This CL replaces it with
the Mojo constant mash::session::mojom::kServiceName.

R=sky@chromium.org
BUG=None

Review-Url: https://codereview.chromium.org/2713223002
Cr-Commit-Position: refs/heads/master@{#452884}

chrome/test/BUILD.gn

@@ -1194,6 +1194,7 @@ static_library("browser_tests_runner") {
 
     deps += [
       "//mash/package",
+      "//mash/session/public/interfaces:constants",
       "//services/service_manager/background:lib",
     ]
 

chrome/test/DEPS

@@ -10,6 +10,7 @@ include_rules = [
   "+device/geolocation",
   "+extensions",
   "+mash/package",
+  "+mash/session/public/interfaces",
   "+mojo",
   "+rlz/features",
   "+services",

chrome/test/base/mash_browser_tests_main.cc

@@ -27,6 +27,7 @@
 #include "content/public/common/service_manager_connection.h"
 #include "content/public/test/test_launcher.h"
 #include "mash/package/mash_packaged_service.h"
+#include "mash/session/public/interfaces/constants.mojom.h"
 #include "services/service_manager/public/cpp/connector.h"
 #include "services/service_manager/public/cpp/service.h"
 #include "services/service_manager/public/cpp/service_context.h"
@@ -43,7 +44,7 @@ const base::FilePath::CharType kCatalogFilename[] =
     FILE_PATH_LITERAL("mash_browser_tests_catalog.json");
 
 void ConnectToDefaultApps(service_manager::Connector* connector) {
-  connector->Connect("mash_session");
+  connector->Connect(mash::session::mojom::kServiceName);
 }
 
 class MashTestSuite : public ChromeTestSuite {