Exclude mojo for Android from a Chrome on Chrome OS coverage build.

There are missing clang runtime libraries that are needed to
successfully link libmojo in a coverage configuration. This
workaround lets us get coverage data for the rest of Chrome on
Chrome OS.

This patch was authored by Noel Gordon, who initially reported this
issue.

Bug: 865376
Change-Id: I88b309760836639b80dfa0f7b67e4bb5c2b55d37
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1493471
Commit-Queue: Sajjad Mirza <sajjadm@google.com>
Reviewed-by: Roberto Carrillo <robertocn@chromium.org>
Reviewed-by: Dirk Pranke <dpranke@chromium.org>
Reviewed-by: Yuke Liao <liaoyuke@chromium.org>
Cr-Commit-Position: refs/heads/master@{#638301}

chrome/BUILD.gn

@@ -5,6 +5,7 @@
 import("//build/config/chrome_build.gni")
 import("//build/config/compiler/compiler.gni")
 import("//build/config/compiler/pgo/pgo.gni")
+import("//build/config/coverage/coverage.gni")
 import("//build/config/features.gni")
 import("//build/config/linux/pangocairo/pangocairo.gni")
 import("//build/config/locales.gni")
@@ -309,7 +310,9 @@ if (!is_android && !is_mac) {
         data_deps += [ "//mojo/core:shared_library" ]
       }
 
-      if (is_chromeos) {
+      # We skip building mojo for ARC in a coverage build because we lack clang
+      # runtime profiling libraries for Android. crbug.com/865376
+      if (is_chromeos && !use_clang_coverage) {
         data_deps += [ "//mojo/core:shared_libraries_for_arc" ]
       }