feat(platform-server): add an API to transfer state from server (#19134)

TransferState provides a shared store that is transferred from the
server to client. To use it import BrowserTransferStateModule from the
client app module and ServerTransferStateModule from the server app
module and TransferState will be available as an Injectable object.

PR Close #19134

tools/cjs-jasmine/index.ts

@@ -73,6 +73,7 @@ var specFiles: any =
         .concat(glob.sync('@angular/platform-browser/test/security/**/*_spec.js', {cwd: distAll}))
         .concat(['/@angular/platform-browser/test/browser/meta_spec.js'])
         .concat(['/@angular/platform-browser/test/browser/title_spec.js'])
+        .concat(['/@angular/platform-browser/test/browser/transfer_state_spec.js'])
         .reduce((specFiles: string[], paths: string[]) => specFiles.concat(paths), <string[]>[]);
 
 jasmine.DEFAULT_TIMEOUT_INTERVAL = 100;

tools/public_api_guard/platform-browser/platform-browser.d.ts

@@ -6,6 +6,10 @@ export declare class BrowserModule {
     }): ModuleWithProviders;
 }
 
+/** @experimental */
+export declare class BrowserTransferStateModule {
+}
+
 /** @experimental */
 export declare class By {
     static all(): Predicate<DebugElement>;
@@ -55,6 +59,9 @@ export declare class HammerGestureConfig {
     buildHammer(element: HTMLElement): HammerInstance;
 }
 
+/** @experimental */
+export declare function makeStateKey<T =
+
 /** @experimental */
 export declare class Meta {
     constructor(_doc: any);
@@ -109,6 +116,11 @@ export interface SafeUrl extends SafeValue {
 export interface SafeValue {
 }
 
+/** @experimental */
+export declare type StateKey<T> = string & {
+    __not_a_string: never;
+};
+
 /** @experimental */
 export declare class Title {
     constructor(_doc: any);
@@ -116,5 +128,15 @@ export declare class Title {
     setTitle(newTitle: string): void;
 }
 
+/** @experimental */
+export declare class TransferState {
+    get<T>(key: StateKey<T>, defaultValue: T): T;
+    hasKey<T>(key: StateKey<T>): boolean;
+    onSerialize<T>(key: StateKey<T>, callback: () => T): void;
+    remove<T>(key: StateKey<T>): void;
+    set<T>(key: StateKey<T>, value: T): void;
+    toJson(): string;
+}
+
 /** @stable */
 export declare const VERSION: Version;

tools/public_api_guard/platform-server/platform-server.d.ts

@@ -41,5 +41,9 @@ export declare function renderModuleFactory<T>(moduleFactory: NgModuleFactory<T>
 export declare class ServerModule {
 }
 
+/** @experimental */
+export declare class ServerTransferStateModule {
+}
+
 /** @stable */
 export declare const VERSION: Version;