Reland of: Allow base to depend on allocator

base/BUILD.gn

Index: base/BUILD.gn
diff --git a/base/BUILD.gn b/base/BUILD.gn
index fe8ad8660e2ebf643367420b9bab51f28fd00385..3f8380c78255abc03d6bf895b80f058b2ce277c5 100644
--- a/base/BUILD.gn
+++ b/base/BUILD.gn
@@ -953,6 +953,7 @@ component("base") {
   ]
 
   deps = [
+    "//base/allocator",
     "//base/third_party/dynamic_annotations",
     "//third_party/modp_b64",
   ]
@@ -1861,7 +1862,6 @@ test("base_unittests") {
     ":message_loop_tests",
     ":prefs",
     ":prefs_test_support",
-    "//base/allocator",
     "//base/test:run_all_unittests",
     "//base/test:test_support",
     "//base/third_party/dynamic_annotations",
@@ -1870,6 +1870,9 @@ test("base_unittests") {
     "//third_party/icu",
   ]
 
+  # Some unittests depend on the ALLOCATOR_SHIM macro.
+  configs += [ "//base/allocator:allocator_shim_define" ]
+
   data = [
     "test/data/",
   ]