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

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

Change-Id: I95a3f3dae4796e4a7beb77793a6101f433a2c649
Reviewed-on: https://chromium-review.googlesource.com/789718
Reviewed-by: Daniel Cheng <[email protected]>
Commit-Queue: Chris Watkins <[email protected]>
Cr-Commit-Position: refs/heads/master@{#520033}
diff --git a/base/tuple_unittest.cc b/base/tuple_unittest.cc
index 730985c..321c549 100644
--- a/base/tuple_unittest.cc
+++ b/base/tuple_unittest.cc
@@ -16,14 +16,14 @@
 }
 
 struct Addy {
-  Addy() { }
+  Addy() = default;
   void DoAdd(int a, int b, int c, int d, int* res) {
     *res = a + b + c + d;
   }
 };
 
 struct Addz {
-  Addz() { }
+  Addz() = default;
   void DoAdd(int a, int b, int c, int d, int e, int* res) {
     *res = a + b + c + d + e;
   }
@@ -68,7 +68,7 @@
 struct CopyLogger {
   CopyLogger() { ++TimesConstructed; }
   CopyLogger(const CopyLogger& tocopy) { ++TimesConstructed; ++TimesCopied; }
-  ~CopyLogger() { }
+  ~CopyLogger() = default;
 
   static int TimesCopied;
   static int TimesConstructed;