update_engine: Fix all the "using" declaration usage.

This patch removes unused "using" declarations, that is, declarations
included in a .cc file at a global scope such that "using foo::bar"
that later don't use the identifier "bar" at all.

This also unifies the usage of these identifiers in the .cc files
in favor of using the short name defined by the using declaration.
For example, in several cases the .h refer to a type like
"std::string" because using declarations are forbidden in header
files while the .cc includes "using std::string;" with the purpose
of just writting "string" in the .cc file. Very rarely, the full
identifier is used when a local name ocludes it, for example,
StringVectorToGStrv() and StringVectorToString() in utils.cc named
its argument just "vector" need to refer to std::vector with the
full name. This patch renames those arguments instead.

Finally, it also sorts a few lists of using declarations that weren't
in order.

BUG=None
TEST=FEATURES=test emerge-link update_engine

Change-Id: I30f6b9510ecb7e03640f1951c48d5bb106309840
Reviewed-on: https://chromium-review.googlesource.com/226423
Reviewed-by: Alex Vakulenko <avakulenko@chromium.org>
Commit-Queue: Alex Deymo <deymo@chromium.org>
Tested-by: Alex Deymo <deymo@chromium.org>
diff --git a/zip_unittest.cc b/zip_unittest.cc
index c73d28d..72fb9a6 100644
--- a/zip_unittest.cc
+++ b/zip_unittest.cc
@@ -22,14 +22,14 @@
 template <typename T>
 class ZipTest : public ::testing::Test {
  public:
-  bool ZipDecompress(const std::vector<char>& in,
-                     std::vector<char>* out) const = 0;
-  bool ZipCompress(const std::vector<char>& in,
-                   std::vector<char>* out) const = 0;
-  bool ZipCompressString(const std::string& str,
-                         std::vector<char>* out) const = 0;
-  bool ZipDecompressString(const std::string& str,
-                           std::vector<char>* out) const = 0;
+  bool ZipDecompress(const vector<char>& in,
+                     vector<char>* out) const = 0;
+  bool ZipCompress(const vector<char>& in,
+                   vector<char>* out) const = 0;
+  bool ZipCompressString(const string& str,
+                         vector<char>* out) const = 0;
+  bool ZipDecompressString(const string& str,
+                           vector<char>* out) const = 0;
 };
 
 class BzipTest {};
@@ -37,20 +37,20 @@
 template <>
 class ZipTest<BzipTest> : public ::testing::Test {
  public:
-  bool ZipDecompress(const std::vector<char>& in,
-                     std::vector<char>* out) const {
+  bool ZipDecompress(const vector<char>& in,
+                     vector<char>* out) const {
     return BzipDecompress(in, out);
   }
-  bool ZipCompress(const std::vector<char>& in,
-                   std::vector<char>* out) const {
+  bool ZipCompress(const vector<char>& in,
+                   vector<char>* out) const {
     return BzipCompress(in, out);
   }
-  bool ZipCompressString(const std::string& str,
-                         std::vector<char>* out) const {
+  bool ZipCompressString(const string& str,
+                         vector<char>* out) const {
     return BzipCompressString(str, out);
   }
-  bool ZipDecompressString(const std::string& str,
-                           std::vector<char>* out) const {
+  bool ZipDecompressString(const string& str,
+                           vector<char>* out) const {
     return BzipDecompressString(str, out);
   }
 };