VR: Fix the UI module factory to use "_partition"-named libraries

The module system added a suffix to libraries to better identify them as
partitions.  VR's factory needs to be updated to work with this
convention.

There is an open bug tracking moving VR to be opened by the module
system.  Once that's done, this issue can't happen again.

Bug: 1023634
Change-Id: I690fd1cc14e957818571a1b0384186d807d3d0f8
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1912633Reviewed-by: Klaus Weidner <klausw@chromium.org>
Commit-Queue: Christopher Grant <cjgrant@chromium.org>
Cr-Commit-Position: refs/heads/master@{#714661}

chrome/browser/android/vr/ui_module_factory.cc

@@ -34,12 +34,12 @@ std::unique_ptr<UiInterface> UiModuleFactory::Create(
   // make it tolerant of two different variants of the VR lib (one for Chrome,
   // one for Monochrome).
   const std::vector<const std::string> library_name_possibilities = {
-      "monochrome_vr",
-      "chrome_vr",
+      "monochrome_vr_partition",
+      "chrome_vr_partition",
   };
 
   void* ui_library_handle = nullptr;
-  const std::string partition_name = "vr";
+  const std::string partition_name = "vr_partition";
   for (const auto& library_name : library_name_possibilities) {
     ui_library_handle =
         base::android::BundleUtils::DlOpenModuleLibraryPartition(