Run clang-tidy modernize-use-equals-{delete,default} on //net/log

See the bugs and cxx post for justification and details:
https://groups.google.com/a/chromium.org/forum/#!topic/cxx/RkOHzIK6Tq8

This change was done using clang-tidy as described here:
https://chromium.googlesource.com/chromium/src/+/lkcr/docs/clang_tidy.md

In some cases the the tool leaves behind a string of commas where it
replaced a member initializer list
(https://bugs.llvm.org/show_bug.cgi?id=35051). They were cleaned up with:
  git diff --name-only | \
    xargs sed -E -i 's/(^\s*|\)\s*):[ ,]*= default/\1 = default/'

BUG=778959,778957
This CL was uploaded by git cl split.

[email protected]

Change-Id: I95be755819bd151634e88ca26016e102d4d02f27
Reviewed-on: https://chromium-review.googlesource.com/799014
Reviewed-by: Bence Béky <[email protected]>
Commit-Queue: Chris Watkins <[email protected]>
Cr-Commit-Position: refs/heads/master@{#521262}
diff --git a/net/log/file_net_log_observer.cc b/net/log/file_net_log_observer.cc
index 3feaa97..5778786 100644
--- a/net/log/file_net_log_observer.cc
+++ b/net/log/file_net_log_observer.cc
@@ -462,7 +462,7 @@
   memory_ = 0;
 }
 
-FileNetLogObserver::WriteQueue::~WriteQueue() {}
+FileNetLogObserver::WriteQueue::~WriteQueue() = default;
 
 FileNetLogObserver::FileWriter::FileWriter(
     const base::FilePath& log_path,
@@ -476,7 +476,7 @@
       wrote_event_bytes_(false),
       task_runner_(std::move(task_runner)) {}
 
-FileNetLogObserver::FileWriter::~FileWriter() {}
+FileNetLogObserver::FileWriter::~FileWriter() = default;
 
 void FileNetLogObserver::FileWriter::Initialize(
     std::unique_ptr<base::Value> constants_value) {