Update UKM network annotation after Unity changes

The unified consent changes the settings required to enable UKM collection.
Unity adds a setting 'Makes searching and browsing better' that directly
controls whether UKM is enabled instead of relying on the sync state.

The UKM code has two different ways of determining the feature state
depending on whether Unity is enabled or not. Unity is going to be enabled
by default in M77 on all platforms but ChromeOS that still uses the old
model.

Bug: 951781
Change-Id: I0caa9503e4e9446f35b4d59940b19c1eb26a1a6a
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1642552
Reviewed-by: Robert Kaplow (slow) <rkaplow@chromium.org>
Reviewed-by: Ramin Halavati <rhalavati@chromium.org>
Reviewed-by: Mihai Sardarescu <msarda@chromium.org>
Commit-Queue: Alex Ilin <alexilin@chromium.org>
Cr-Original-Commit-Position: refs/heads/master@{#666790}
Cr-Mirrored-From: https://chromium.googlesource.com/chromium/src
Cr-Mirrored-Commit: ed532c99bf2339da7abc600497c9d7a4f14ddea1
diff --git a/net/net_metrics_log_uploader.cc b/net/net_metrics_log_uploader.cc
index c86b269..205fd59 100644
--- a/net/net_metrics_log_uploader.cc
+++ b/net/net_metrics_log_uploader.cc
@@ -102,21 +102,21 @@
         })");
   }
   DCHECK_EQ(service_type, metrics::MetricsLogUploader::UKM);
+  // TODO(https://crbug.com/951781): Update this annotation once Unity is
+  // enabled on ChromeOS by default.
   return net::DefineNetworkTrafficAnnotation("metrics_report_ukm", R"(
       semantics {
         sender: "Metrics UKM Log Uploader"
         description:
-          "Report of usage statistics that are keyed by URLs to Chromium, "
-          "sent only if the profile has History Sync. This includes "
-          "information about the web pages you visit and your usage of them, "
-          "such as page load speed. This will also include URLs and "
-          "statistics related to downloaded files. If Extension Sync is "
-          "enabled, these statistics will also include information about "
-          "the extensions that have been installed from Chrome Web Store. "
-          "Google only stores usage statistics associated with published "
-          "extensions, and URLs that are known by Google’s search index. "
-          "Usage statistics are tied to a pseudonymous machine identifier "
-          "and not to your email address."
+          "Report of usage statistics that are keyed by URLs to Chromium. This "
+          "includes information about the web pages you visit and your usage "
+          "of them, such as page load speed. This will also include URLs and "
+          "statistics related to downloaded files. These statistics may also "
+          "include information about the extensions that have been installed "
+          "from Chrome Web Store. Google only stores usage statistics "
+          "associated with published extensions, and URLs that are known by "
+          "Google’s search index. Usage statistics are tied to a "
+          "pseudonymous machine identifier and not to your email address."
         trigger:
           "Reports are automatically generated on startup and at intervals "
           "while Chromium is running with Sync enabled."
@@ -127,11 +127,19 @@
       policy {
         cookies_allowed: NO
         setting:
-          "Users can enable or disable this feature by disabling "
-          "'Automatically send usage statistics and crash reports to Google' "
-          "in Chromium's settings under Advanced Settings, Privacy. This is "
-          "only enabled if all active profiles have History/Extension Sync "
-          "enabled without a Sync passphrase."
+          "On ChromeOS, users can enable or disable this feature by disabling "
+          "'Automatically send diagnostic and usage data to Google' in "
+          "Chrome's settings under Advanced Settings, Privacy. This is only "
+          "enabled if all active profiles have History Sync enabled without a "
+          "Sync passphrase. "
+          "On all other platforms, users can enable or disable this feature by "
+          "disabling 'Make searches and browsing better' in Chrome's settings "
+          "under Advanced Settings, Privacy. This has to be enabled for all "
+          "active profiles. This is only enabled if the user has "
+          "'Help improve Chrome's features and performance' enabled in the "
+          "same settings menu. "
+          "On all platforms, information about the installed extensions is "
+          "sent only if Extension Sync is enabled."
         chrome_policy {
           MetricsReportingEnabled {
             policy_options {mode: MANDATORY}