[web] extend history debugging with estimate on snapshot size (#32502)

GitOrigin-RevId: 6ee75d227c0d093e4698324f6cc018b077076730

services/web/frontend/js/infrastructure/project-snapshot.ts

@@ -256,7 +256,7 @@ export class ProjectSnapshot {
 /**
  * Blob store that fetches blobs from the history service
  */
-class SimpleBlobStore {
+export class SimpleBlobStore {
   private projectId: string
 
   constructor(projectId: string) {
@@ -280,7 +280,7 @@ async function flushHistory(projectId: string) {
   await postJSON(`/project/${projectId}/flush`)
 }
 
-async function fetchLatestChunk(projectId: string): Promise<Chunk> {
+export async function fetchLatestChunk(projectId: string): Promise<Chunk> {
   const response = await getJSON<{ chunk: RawChunk }>(
     `/project/${projectId}/latest/history`
   )