Add LogDog log stream fetcher code.

web/inc/rpc/client.ts

Index: web/inc/rpc/client.ts
diff --git a/web/inc/rpc/client.ts b/web/inc/rpc/client.ts
index 9d3928ff54b2de3008a4d84a11a3adcb5b94f042..c29decffa18ec856b995083578972db93da24853 100644
--- a/web/inc/rpc/client.ts
+++ b/web/inc/rpc/client.ts
@@ -216,14 +216,14 @@ namespace luci {
   export type Retry = {
     // The number of retries to perform before failing. If undefined, will retry
     // indefinitely.
-    retries: number | undefined;
+    retries?: number;
 
     // The amount of time to delay in between retry attempts, in milliseconds.
     // If undefined or < 0, no delay will be imposed.
     delay: number;
     // The maximum delay to apply, in milliseconds. If > 0 and delay scales past
     // "maxDelay", it will be capped at "maxDelay".
-    maxDelay: number | undefined;
+    maxDelay?: number;
 
     // delayScaling is the multiplier applied to "delay" in between retries. If
     // undefined or <= 1, DEFAULT_DELAY_SCALING will be used.