Replace ASSERT by RTC_DCHECK in all non-test code.

Bulk of the changes were produced using

  git grep -l ' ASSERT(' | grep -v test | grep -v 'common\.h' |\
    xargs -n1 sed -i 's/ ASSERT(/ RTC_DCHECK(/'

followed by additional includes of base/checks.h in affected files,
and git cl format.

Also had to do some tweaks to #if !defined(NDEBUG) logic in the
taskrunner code (webrtc/base/task.cc, webrtc/base/taskparent.cc,
webrtc/base/taskparent.h, webrtc/base/taskrunner.cc), replaced to
consistently use RTC_DCHECK_IS_ON, and some of the checks needed
additional #if protection.

Test code was excluded, because it should probably use RTC_CHECK
rather than RTC_DCHECK.

BUG=webrtc:6424

Review-Url: https://codereview.webrtc.org/2620303003
Cr-Commit-Position: refs/heads/master@{#16030}
diff --git a/webrtc/base/win32.cc b/webrtc/base/win32.cc
index 182b84f..7dfff42 100644
--- a/webrtc/base/win32.cc
+++ b/webrtc/base/win32.cc
@@ -17,6 +17,7 @@
 #include "webrtc/base/arraysize.h"
 #include "webrtc/base/basictypes.h"
 #include "webrtc/base/byteorder.h"
+#include "webrtc/base/checks.h"
 #include "webrtc/base/common.h"
 #include "webrtc/base/logging.h"
 
@@ -318,7 +319,7 @@
 //
 
 void FileTimeToUnixTime(const FILETIME& ft, time_t* ut) {
-  ASSERT(NULL != ut);
+  RTC_DCHECK(NULL != ut);
 
   // FILETIME has an earlier date base than time_t (1/1/1970), so subtract off
   // the difference.
@@ -342,7 +343,7 @@
 }
 
 void UnixTimeToFileTime(const time_t& ut, FILETIME* ft) {
-  ASSERT(NULL != ft);
+  RTC_DCHECK(NULL != ft);
 
   // FILETIME has an earlier date base than time_t (1/1/1970), so add in
   // the difference.
@@ -404,13 +405,13 @@
     // Non-unc path:     <pathname>
     //      Becomes: \\?\<pathname>
     start -= 4;
-    ASSERT(start >= full_filename);
+    RTC_DCHECK(start >= full_filename);
     memcpy(start, kLongPathPrefix, 4 * sizeof(wchar_t));
   } else if (start[2] != L'?') {
     // Unc path:       \\<server>\<pathname>
     //  Becomes: \\?\UNC\<server>\<pathname>
     start -= 6;
-    ASSERT(start >= full_filename);
+    RTC_DCHECK(start >= full_filename);
     memcpy(start, kLongPathPrefix, 7 * sizeof(wchar_t));
   } else {
     // Already in long-path form.