Change ContentLinker to share relro sections with browser process only on low-end devices.

While this change increases memory usage on non low-end devices, the
impact is small enough that we can limit the exposure surface to only
where it makes a signficant impact.

Also adds content_linker_test_apk to the android builders to ensure it
doesn't regress.

Review URL: https://codereview.chromium.org/139743011

git-svn-id: http://src.chromium.org/svn/trunk/src/build@247622 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

all.gyp

@@ -726,6 +726,7 @@
             '../components/components_tests.gyp:components_unittests',
             '../content/content_shell_and_tests.gyp:content_browsertests',
             '../content/content_shell_and_tests.gyp:content_gl_tests',
+            '../content/content_shell_and_tests.gyp:content_linker_test_apk',
             '../content/content_shell_and_tests.gyp:content_shell_test_apk',
             '../content/content_shell_and_tests.gyp:content_unittests',
             '../gpu/gpu.gyp:gl_tests',