Add mimeType and stringifyStep to Recorder extension API

mimeType would be needed for syntax highlighting and file extension
generation. And stringifyStep for partial stringification.

Bug: 1325751
Change-Id: I2a8c7c55cf5c8ea299a5e133725ce59e6ea69dad
Reviewed-on: https://chromium-review.googlesource.com/c/devtools/devtools-frontend/+/3683218
Commit-Queue: Alex Rudenko <alexrudenko@chromium.org>
Reviewed-by: Philip Pfaffe <pfaffe@chromium.org>
diff --git a/extension-api/ExtensionAPI.d.ts b/extension-api/ExtensionAPI.d.ts
index ba9d736..09a435a 100644
--- a/extension-api/ExtensionAPI.d.ts
+++ b/extension-api/ExtensionAPI.d.ts
@@ -172,7 +172,8 @@
     }
 
     export interface RecorderExtensionPlugin {
-      stringify(obj: Record<string, any>): Promise<string>;
+      stringify(recording: Record<string, any>): Promise<string>;
+      stringifyStep(step: Record<string, any>): Promise<string>;
     }
 
     export interface LanguageExtensionPlugin {
@@ -278,7 +279,8 @@
     }
 
     export interface RecorderExtensions {
-      registerRecorderExtensionPlugin(plugin: RecorderExtensionPlugin, pluginName: string): Promise<void>;
+      registerRecorderExtensionPlugin(plugin: RecorderExtensionPlugin, pluginName: string, mimeType: string):
+          Promise<void>;
       unregisterRecorderExtensionPlugin(plugin: RecorderExtensionPlugin): Promise<void>;
     }