Eliminate build warnings in base/ for Android x64

This CL fixes format strings of printf and type conversions
that cause compilation warnings while building Android x64.

BUG=346626

Review URL: https://codereview.chromium.org/185423006

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@257942 0039d316-1c4b-4281-b951-d872f2087c98
diff --git a/base/strings/string_piece_unittest.cc b/base/strings/string_piece_unittest.cc
index d45fd92..7f50cfb 100644
--- a/base/strings/string_piece_unittest.cc
+++ b/base/strings/string_piece_unittest.cc
@@ -674,9 +674,11 @@
   ASSERT_TRUE(str == BasicStringPiece<TypeParam>(str.c_str()));
   ASSERT_TRUE(TestFixture::as_string("hello") ==
               BasicStringPiece<TypeParam>(str.c_str(), 5));
-  ASSERT_TRUE(empty == BasicStringPiece<TypeParam>(str.c_str(), 0U));
+  ASSERT_TRUE(empty == BasicStringPiece<TypeParam>(str.c_str(),
+      static_cast<typename BasicStringPiece<TypeParam>::size_type>(0)));
   ASSERT_TRUE(empty == BasicStringPiece<TypeParam>(NULL));
-  ASSERT_TRUE(empty == BasicStringPiece<TypeParam>(NULL, 0U));
+  ASSERT_TRUE(empty == BasicStringPiece<TypeParam>(NULL,
+      static_cast<typename BasicStringPiece<TypeParam>::size_type>(0)));
   ASSERT_TRUE(empty == BasicStringPiece<TypeParam>());
   ASSERT_TRUE(str == BasicStringPiece<TypeParam>(str.begin(), str.end()));
   ASSERT_TRUE(empty == BasicStringPiece<TypeParam>(str.begin(), str.begin()));