Update from https://crrev.com/319330
- New chromium clang rules require explicit external destructors so
  system/lib added for MessagePipe, DataPipe and SharedBuffer
- New chromium clang rules require override and no virtual in
  declarations, so many files updated.
- cc_strip_video patch updated.

BUG=
R=jamesr@chromium.org

Review URL: https://codereview.chromium.org/988693005
diff --git a/shell/app_child_process.cc b/shell/app_child_process.cc
index 0054037..387aa5f 100644
--- a/shell/app_child_process.cc
+++ b/shell/app_child_process.cc
@@ -84,7 +84,7 @@
  public:
   AppContext()
       : io_thread_("io_thread"), controller_thread_("controller_thread") {}
-  ~AppContext() {}
+  ~AppContext() override {}
 
   void Init() {
     // Initialize Mojo before starting any threads.