Try to fix duplicate symbol errors for tts_platform_fuzzer.

It looks like the dep on //content/public/browser:browser_sources
isn't needed (and causes link problems); it was merely there to placate
`gn check`. Instead, suppress `gn check` for this target and file
a bug to fix the issues pointed out by `gn check` for real instead
of incorrectly papering over them with this dep.

Bug: 927713
Change-Id: If4d991a4961fd36937b75c442514d349d5d60ab0
Reviewed-on: https://chromium-review.googlesource.com/c/1449816
Auto-Submit: Nico Weber <thakis@chromium.org>
Reviewed-by: Jochen Eisinger <jochen@chromium.org>
Commit-Queue: Jochen Eisinger <jochen@chromium.org>
Cr-Commit-Position: refs/heads/master@{#628322}

content/test/fuzzer/BUILD.gn

@@ -210,10 +210,12 @@ if (is_win) {
       "//content/common/content_export.h",
     ]
 
+    # TODO(https://crbug.com/927728): Refactor target to not require this.
+    check_includes = false
+
     deps = [
       "//base",
       "//base/test:test_support",
-      "//content/public/browser:browser_sources",
       "//ui/base",
       "//url:url",
     ]