[MediaRouter] Add ROUTE_ALREADY_EXISTS result code.

This will be used for in-browser DIAL MRP
(https://chromium-review.googlesource.com/c/chromium/src/+/1036611) and
other future MRP implementations to indicate a MediaRoute already
exists when trying to CreateRoute.

Bug: 816628
Change-Id: Id43d91be7318362043cc33a3c0500cc9463f5a5d
Reviewed-on: https://chromium-review.googlesource.com/1062145Reviewed-by: Adam Parker <amp@chromium.org>
Reviewed-by: Daniel Cheng <dcheng@chromium.org>
Commit-Queue: Derek Cheng <imcheng@chromium.org>
Cr-Commit-Position: refs/heads/master@{#559249}

chrome/common/media_router/mojo/media_router.mojom

@@ -199,7 +199,7 @@ struct SinkSearchCriteria {
 // - RouteRequestResult::ResultCode in route_request_result.h
 // - MediaRouteProviderResult enum in tools/metrics/histograms.xml.
 // - mr.RouteRequestResultCode in route_request_error.js
-// - RouteRequestResultCodeFromMojo in media_router_type_converters.cc
+// - media_router_struct_traits.h
 enum RouteRequestResultCode {
   UNKNOWN_ERROR,
   OK,
@@ -209,7 +209,8 @@ enum RouteRequestResultCode {
   INVALID_ORIGIN,
   INCOGNITO_MISMATCH,
   NO_SUPPORTED_PROVIDER,
-  CANCELLED
+  CANCELLED,
+  ROUTE_ALREADY_EXISTS
 // New values must be added here.
 };
 

chrome/common/media_router/mojo/media_router_struct_traits.h

@@ -473,6 +473,9 @@ struct EnumTraits<media_router::mojom::RouteRequestResultCode,
             NO_SUPPORTED_PROVIDER;
       case media_router::RouteRequestResult::CANCELLED:
         return media_router::mojom::RouteRequestResultCode::CANCELLED;
+      case media_router::RouteRequestResult::ROUTE_ALREADY_EXISTS:
+        return media_router::mojom::RouteRequestResultCode::
+            ROUTE_ALREADY_EXISTS;
       default:
         NOTREACHED() << "Unknown RouteRequestResultCode "
                      << static_cast<int>(code);
@@ -510,6 +513,9 @@ struct EnumTraits<media_router::mojom::RouteRequestResultCode,
       case media_router::mojom::RouteRequestResultCode::CANCELLED:
         *output = media_router::RouteRequestResult::CANCELLED;
         return true;
+      case media_router::mojom::RouteRequestResultCode::ROUTE_ALREADY_EXISTS:
+        *output = media_router::RouteRequestResult::ROUTE_ALREADY_EXISTS;
+        return true;
     }
     return false;
   }

chrome/common/media_router/route_request_result.h

@@ -35,7 +35,7 @@ class RouteRequestResult {
   // - RouteRequestResultCode in media_router.mojom
   // - MediaRouteProviderResult enum in tools/metrics/histograms.xml
   // - mr.RouteRequestResultCode in route_request_error.js
-  // - RouteRequestResultCodeFromMojo in media_router_type_converters.cc
+  // - media_router_struct_traits.h
   enum ResultCode {
     UNKNOWN_ERROR = 0,
     OK = 1,
@@ -46,9 +46,10 @@ class RouteRequestResult {
     INCOGNITO_MISMATCH = 6,
     NO_SUPPORTED_PROVIDER = 7,
     CANCELLED = 8,
+    ROUTE_ALREADY_EXISTS = 9,
     // New values must be added here.
 
-    TOTAL_COUNT = 9  // The total number of values.
+    TOTAL_COUNT = 10  // The total number of values.
   };
 
   static std::unique_ptr<RouteRequestResult> FromSuccess(

tools/metrics/histograms/enums.xml

@@ -29656,6 +29656,7 @@ Called by update_use_counter_css.py.-->
   <int value="6" label="OffTheRecordMismatch"/>
   <int value="7" label="NoSupportedProvider"/>
   <int value="8" label="Cancelled"/>
+  <int value="9" label="RouteAlreadyExists"/>
 </enum>
 
 <enum name="MediaRouteProviderVersion">