Add a Mojo EDK for Chrome that uses one OS pipe per message pipe.

content/test/BUILD.gn

Index: content/test/BUILD.gn
diff --git a/content/test/BUILD.gn b/content/test/BUILD.gn
index 75c16e885c3c795558a9ced930e2a029c9e7a52e..af53fb4efaf766a07ca6bb3b3209a0e71458eec8 100644
--- a/content/test/BUILD.gn
+++ b/content/test/BUILD.gn
@@ -352,8 +352,6 @@ if (!is_mac) {
       "//ppapi/proxy",
       "//ppapi/proxy:ipc",
       "//ppapi/shared_impl",
-      "//third_party/mojo/src/mojo/edk/system",
-      "//third_party/mojo/src/mojo/edk/test:test_support",
       "//third_party/mojo/src/mojo/public/cpp/bindings",
       "//third_party/mojo/src/mojo/public/js",
       "//testing/gmock",
@@ -375,6 +373,18 @@ if (!is_mac) {
       "//ui/snapshot",
     ]
 
+    if (use_chrome_edk) {
+      deps += [
+        "//mojo/edk/system",
+        "//mojo/edk/test:test_support",
+      ]
+    } else {
+      deps += [
+        "//third_party/mojo/src/mojo/edk/system",
+        "//third_party/mojo/src/mojo/edk/test:test_support",
+      ]
+    }
+
     data_deps = [
       "//ppapi:ppapi_tests",
       "//third_party/mesa:osmesa",
@@ -533,7 +543,6 @@ test("content_unittests") {
     "//sql:test_support",
     "//testing/gmock",
     "//testing/gtest",
-    "//third_party/mojo/src/mojo/edk/test:test_support",
     "//third_party/mojo/src/mojo/public/cpp/bindings",
     "//third_party/re2",
     "//ui/accessibility",
@@ -544,6 +553,12 @@ test("content_unittests") {
     "//ui/gfx/ipc",
   ]
 
+  if (use_chrome_edk) {
+    deps += [ "//mojo/edk/test:test_support" ]
+  } else {
+    deps += [ "//third_party/mojo/src/mojo/edk/test:test_support" ]
+  }
+
   if (!is_ios) {
     deps += [
       "//base/third_party/dynamic_annotations",