Remove base's implicit_cast.

There's no momentum on making this a thing in the C++ standard. We
should have less magic that is non-standard in base.

R=ricea@chromium.org, thakis@chromium.org, vmpstr
BUG=529769

Review URL: https://codereview.chromium.org/1340683002

Cr-Commit-Position: refs/heads/master@{#348978}


CrOS-Libchrome-Original-Commit: a5f0d96bc4f40971fc82e0b2255e27056d4621d1
diff --git a/base/files/file_unittest.cc b/base/files/file_unittest.cc
index 5c59424..3d60b2c 100644
--- a/base/files/file_unittest.cc
+++ b/base/files/file_unittest.cc
@@ -517,7 +517,7 @@
     // Test that changing the checksum value is detected.
     base::File file;
     EXPECT_NE(file.file_.file_memory_checksum_,
-              implicit_cast<unsigned int>(file.GetPlatformFile()));
+              static_cast<unsigned int>(file.GetPlatformFile()));
     file.file_.file_memory_checksum_ = file.GetPlatformFile();
     EXPECT_DEATH(file.IsValid(), "");