Network traffic annotation added to image_data_fetcher.

components/favicon/core/large_icon_service.cc

Index: components/favicon/core/large_icon_service.cc
diff --git a/components/favicon/core/large_icon_service.cc b/components/favicon/core/large_icon_service.cc
index bf94e5b38ea09f0ccbe059df76ed3984f6c62e80..6f90d13042a0b735f4fad0359d8b967519b1af9b 100644
--- a/components/favicon/core/large_icon_service.cc
+++ b/components/favicon/core/large_icon_service.cc
@@ -339,10 +339,30 @@ void LargeIconService::
 
   image_fetcher_->SetDataUseServiceName(
       data_use_measurement::DataUseUserData::LARGE_ICON_SERVICE);
+  net::NetworkTrafficAnnotationTag traffic_annotation =
+      net::DefineNetworkTrafficAnnotation("favicon_component", R"(
+        semantics {
+          sender: "Favicon Component"
+          description:
+            "Sends a request to a Google server to retrieve the favicon bitmap "

[msramek, 2017/05/18 11:25:18]

Since the payload is sensitive, can you please elaborate more where the URL
comes from?

[pkotwicz, 2017/05/18 15:47:43]

There are multiple places where the payload can come from as
GetLargeIconOrFallbackStyleFromGoogleServerSkippingLocalCache() is used by
multiple call sites

Currently the NTP is the only caller for NTP thumbnails and content suggestions.
I think that the iOS folks want to use this for bookmarks. In crbug.com/672478
there is a proposal of using this function for passwords in chrome://settings

[msramek, 2017/05/18 16:02:16]

So, my point is that we generally only share user's URLs with Google if history
sync is enabled. Since history sync is not listed as a setting that controls
this request, I would like this annotation to justify the cases where we send
URL without history sync enabled.

Please don't worry about the future proposals now - they will have to go through
a privacy review, where we can remind them to update the annotation.

If you think that the callers are too varied to be listed here, perhaps we
should split annotation so that the description is defined on upper layers. This
is not supported right now, but will be soon.

[jkrcal, 2017/05/19 06:18:21]

I would replace the "For instance, ..." sentence by:
This is used:
 - for article suggestions on the new tab page (URLs are public and provided by
Google),
 - for server-suggested most visited tiles on the new tab page (user gets these
URLs from Google, only if history sync is enabled).

I agree with privacy requiring each new user to update the annotation. 

[Ramin Halavati, 2017/05/19 06:37:37]

Done.

+            "for a page URL."
+          trigger:
+            "A request can be sent for signed-in users when Chrome does not "
+            "have a favicon for a particular page. For instance, this is used "
+            "by the new tab page for the 'most visited' tiles."
+          data: "Page URL and desired icon size."
+          destination: GOOGLE_OWNED_SERVICE
+        }
+        policy {
+          cookies_allowed: false
+          setting: "This feature cannot be disabled by settings."
+          policy_exception_justification: "Not implemented."
+        })");
   image_fetcher_->StartOrQueueNetworkRequest(
       server_request_url.spec(), server_request_url,
       base::Bind(&OnFetchIconFromGoogleServerComplete, favicon_service_,
-                 page_url, callback));
+                 page_url, callback),
+      traffic_annotation);
 }
 
 base::CancelableTaskTracker::TaskId