Convert string class names

Automated using git grep & sed.
Replace StringC classes with StringView classes.
Remove the CFX_ prefix and put string classes in fxcrt namespace.
Change AsStringC() to AsStringView().
Rename tests from TEST(fxcrt, *String*Foo) to TEST(*String*,
Foo).
Couple of tests needed to have their names regularlized.

BUG=pdfium:894

Change-Id: I7ca038685c8d803795f3ed02545124f7a224c83d
Reviewed-on: https://pdfium-review.googlesource.com/14151
Reviewed-by: Tom Sepez <tsepez@chromium.org>
Commit-Queue: Ryan Harrison <rharrison@chromium.org>
diff --git a/fxbarcode/cbc_datamatrix.cpp b/fxbarcode/cbc_datamatrix.cpp
index 91ed10e..c9e23fa 100644
--- a/fxbarcode/cbc_datamatrix.cpp
+++ b/fxbarcode/cbc_datamatrix.cpp
@@ -31,12 +31,12 @@
 
 CBC_DataMatrix::~CBC_DataMatrix() {}
 
-bool CBC_DataMatrix::Encode(const CFX_WideStringC& contents) {
+bool CBC_DataMatrix::Encode(const WideStringView& contents) {
   int32_t outWidth = 0;
   int32_t outHeight = 0;
   auto* pWriter = GetDataMatrixWriter();
   std::unique_ptr<uint8_t, FxFreeDeleter> data(
-      pWriter->Encode(CFX_WideString(contents), outWidth, outHeight));
+      pWriter->Encode(WideString(contents), outWidth, outHeight));
   if (!data)
     return false;
   return pWriter->RenderResult(data.get(), outWidth, outHeight);