Add a note to URLFetcher that it shouldn't be use in content embedders.

Also add a presubmit warning to trigger on new/modified uses of
URLFetcher.

Bug: 746977, 598073
Change-Id: I962a9f9bdb0c8c533f5cc4e7ca5a919f917a89ca
Reviewed-on: https://chromium-review.googlesource.com/984512
Reviewed-by: Helen Li <xunjieli@chromium.org>
Reviewed-by: Daniel Cheng <dcheng@chromium.org>
Commit-Queue: Matt Menke <mmenke@chromium.org>
Cr-Commit-Position: refs/heads/master@{#546605}

PRESUBMIT.py

@@ -543,6 +543,24 @@ _BANNED_CPP_FUNCTIONS = (
         r'^third_party/sqlite/.*\.(c|cc|h)$',
       ),
     ),
+    (
+      'net::URLFetcher',
+      (
+        'net::URLFetcher should no longer be used in content embedders. ',
+        'Instead, use network::SimpleURLLoader instead, which supports ',
+        'an out-of-process network stack. ',
+        'net::URLFetcher may still be used in binaries that do not embed',
+        'content.',
+      ),
+      True,
+      (
+        r'^ios[\\\/].*\.(cc|h)$',
+        r'.*[\\\/]ios[\\\/].*\.(cc|h)$',
+        r'.*_ios\.(cc|h)$',
+        r'^net[\\\/].*\.(cc|h)$',
+        r'.*[\\\/]tools[\\\/].*\.(cc|h)$',
+      ),
+    ),
 )
 
 

net/url_request/url_fetcher.h

@@ -39,6 +39,11 @@ class URLFetcherResponseWriter;
 class URLRequestContextGetter;
 class URLRequestStatus;
 
+// NOTE:  This class should not be used by content embedders, as it requires an
+// in-process network stack. Content embedders should use
+// network::SimpleURLLoader instead, which works with both in-process and
+// out-of-process network stacks.
+//
 // To use this class, create an instance with the desired URL and a pointer to
 // the object to be notified when the URL has been loaded:
 //   std::unique_ptr<URLFetcher> fetcher =