Mark classes with final dtors as final

- -Wfinal-dtor-non-final-class warns on classes with final dtors but
  not final classes.
- Error messages are better when the class is marked final.
- Fix existing issues in code base and remove warning exemption

Bug: 999886
Test: no errors building
Change-Id: I0814e4c543eb7f6d25bb0dfc1990b30e0b0c2f80
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2468299
Commit-Queue: Zentaro Kavanagh <zentaro@chromium.org>
Commit-Queue: Nico Weber <thakis@chromium.org>
Reviewed-by: Reilly Grant <reillyg@chromium.org>
Reviewed-by: Dale Curtis <dalecurtis@chromium.org>
Reviewed-by: Nico Weber <thakis@chromium.org>
Cr-Commit-Position: refs/heads/master@{#827532}

chrome/renderer/plugins/pdf_plugin_placeholder.h

@@ -11,8 +11,8 @@
 // plugins are disabled and the PDF fails to load.
 // TODO(amberwon): Flesh out the class more to download an embedded PDF when the
 // PDF plugin is disabled or unavailable.
-class PDFPluginPlaceholder : public plugins::PluginPlaceholderBase,
-                             public gin::Wrappable<PDFPluginPlaceholder> {
+class PDFPluginPlaceholder final : public plugins::PluginPlaceholderBase,
+                                   public gin::Wrappable<PDFPluginPlaceholder> {
  public:
   static gin::WrapperInfo kWrapperInfo;
 

content/renderer/media/media_interface_factory.h

@@ -29,7 +29,7 @@ namespace content {
 // MediaInterfaceFactory is an implementation of media::mojom::InterfaceFactory
 // that provides thread safety and handles disconnection error automatically.
 // The Create* methods can be called on any thread.
-class CONTENT_EXPORT MediaInterfaceFactory
+class CONTENT_EXPORT MediaInterfaceFactory final
     : public media::mojom::InterfaceFactory {
  public:
   explicit MediaInterfaceFactory(

extensions/renderer/guest_view/guest_view_internal_custom_bindings.cc

@@ -61,7 +61,7 @@ content::RenderFrame* GetRenderFrame(v8::Local<v8::Value> value) {
   return content::RenderFrame::FromWebFrame(frame);
 }
 
-class RenderFrameStatus : public content::RenderFrameObserver {
+class RenderFrameStatus final : public content::RenderFrameObserver {
  public:
   explicit RenderFrameStatus(content::RenderFrame* render_frame)
       : content::RenderFrameObserver(render_frame) {}

services/device/hid/hid_connection_impl.h

@@ -15,8 +15,8 @@ namespace device {
 // HidConnectionImpl is reponsible for handling mojo communications from
 // clients. It delegates to HidConnection the real work of creating
 // connections in different platforms.
-class HidConnectionImpl : public mojom::HidConnection,
-                          public HidConnection::Client {
+class HidConnectionImpl final : public mojom::HidConnection,
+                                public HidConnection::Client {
  public:
   // Creates a strongly-bound HidConnectionImpl owned by |receiver| and
   // |watcher|. |connection| provides access to the HID device. If