Fix comments related to URLLoaderThrottle and threads

Change-Id: I531edc4cbae26cac9ac4dc256d2fcd938c13f3d7
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2062642
Commit-Queue: Kinuko Yasuda <kinuko@chromium.org>
Reviewed-by: Kinuko Yasuda <kinuko@chromium.org>
Cr-Commit-Position: refs/heads/master@{#742889}

content/public/renderer/content_renderer_client.h

@@ -392,7 +392,8 @@ class CONTENT_EXPORT ContentRendererClient {
 
   // Allows the embedder to return a (possibly null) URLLoaderThrottleProvider
   // for a frame or worker. For frames this is called on the main thread, and
-  // for workers it's called on the worker thread.
+  // for workers it's called on the main or worker threads depending on
+  // http://crbug.com/692909.
   virtual std::unique_ptr<URLLoaderThrottleProvider>
   CreateURLLoaderThrottleProvider(URLLoaderThrottleProviderType provider_type);
 

content/public/renderer/url_loader_throttle_provider.h

@@ -31,10 +31,10 @@ class CONTENT_EXPORT URLLoaderThrottleProvider {
   // Used to copy a URLLoaderThrottleProvider between worker threads.
   virtual std::unique_ptr<URLLoaderThrottleProvider> Clone() = 0;
 
-  // For requests from frames and dedicated workers, this is called on the main
-  // thread and |render_frame_id| will be set to the corresponding frame. For
-  // requests from shared or service workers, this is called on the worker
-  // thread and |render_frame_id| will be set to MSG_ROUTING_NONE.
+  // For frame requests this is called on the main thread. Dedicated, shared and
+  // service workers call it on the worker thread. |render_frame_id| will be set
+  // to the corresponding frame for frame and dedicated worker requests,
+  // otherwise it will be MSG_ROUTING_NONE.
   virtual std::vector<std::unique_ptr<blink::URLLoaderThrottle>>
   CreateThrottles(int render_frame_id, const blink::WebURLRequest& request) = 0;