Remove usage of rtc_base/checks.h in 3pp base64.cc

rtc_base/base64.h and rtc_base/base64.cc are third_party files in webrtc
repo and we are planning to move them into third_party folder. To be
able to do it, we need to eliminate all dependencies from this files
on webrtc code base. So thic CL will remove dependency on
rtc_base.checks.h. After it we will be able to move base64 files.

Bug: webrtc:8366
Change-Id: I79d252daef974e95bb43a1566d05e603922aea3f
Reviewed-on: https://webrtc-review.googlesource.com/84126
Commit-Queue: Artem Titov <titovartem@webrtc.org>
Reviewed-by: Taylor Brandstetter <deadbeef@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#23702}
diff --git a/rtc_base/BUILD.gn b/rtc_base/BUILD.gn
index effe58b..e7dfb9e 100644
--- a/rtc_base/BUILD.gn
+++ b/rtc_base/BUILD.gn
@@ -495,10 +495,6 @@
     "base64.cc",
     "base64.h",
   ]
-
-  deps = [
-    ":checks",
-  ]
 }
 
 rtc_source_set("rtc_task_queue") {
diff --git a/rtc_base/base64.cc b/rtc_base/base64.cc
index 0ccec0e..6add993 100644
--- a/rtc_base/base64.cc
+++ b/rtc_base/base64.cc
@@ -17,8 +17,7 @@
 #include "rtc_base/base64.h"
 
 #include <string.h>
-
-#include "rtc_base/checks.h"
+#include <assert.h>
 
 using std::vector;
 
@@ -96,7 +95,7 @@
 void Base64::EncodeFromArray(const void* data,
                              size_t len,
                              std::string* result) {
-  RTC_DCHECK(nullptr != result);
+  assert(nullptr != result);
   result->clear();
   result->resize(((len + 2) / 3) * 4);
   const unsigned char* byte_data = static_cast<const unsigned char*>(data);
@@ -224,15 +223,15 @@
                                      DecodeFlags flags,
                                      T* result,
                                      size_t* data_used) {
-  RTC_DCHECK(nullptr != result);
-  RTC_DCHECK(flags <= (DO_PARSE_MASK | DO_PAD_MASK | DO_TERM_MASK));
+  assert(nullptr != result);
+  assert(flags <= (DO_PARSE_MASK | DO_PAD_MASK | DO_TERM_MASK));
 
   const DecodeFlags parse_flags = flags & DO_PARSE_MASK;
   const DecodeFlags pad_flags = flags & DO_PAD_MASK;
   const DecodeFlags term_flags = flags & DO_TERM_MASK;
-  RTC_DCHECK(0 != parse_flags);
-  RTC_DCHECK(0 != pad_flags);
-  RTC_DCHECK(0 != term_flags);
+  assert(0 != parse_flags);
+  assert(0 != pad_flags);
+  assert(0 != term_flags);
 
   result->clear();
   result->reserve(len);