[base] Only log zx_vmar_map() failure for non-hinted allocations.

Bug: 927411
Change-Id: Ia2fabf76ef8faa3b8d875b8625572c81eef20946
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1911488
Commit-Queue: Wez <wez@chromium.org>
Reviewed-by: Chris Palmer <palmer@chromium.org>
Auto-Submit: Wez <wez@chromium.org>
Cr-Commit-Position: refs/heads/master@{#714668}

base/allocator/partition_allocator/page_allocator_internals_fuchsia.h

@@ -109,7 +109,10 @@ void* SystemAllocPagesInternal(void* hint,
       zx::vmar::root_self()->map(vmar_offset, vmo,
                                  /*vmo_offset=*/0, length, options, &address);
   if (status != ZX_OK) {
-    ZX_DLOG(INFO, status) << "zx_vmar_map";
+    // map() is expected to fail if |hint| is set to an already-in-use location.
+    if (!hint) {
+      ZX_DLOG(ERROR, status) << "zx_vmar_map";
+    }
     return nullptr;
   }