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 a follow up will remove warning
  exemption.

Bug: 999886
Test: no errors building
Change-Id: I05f4526ee929fdab498f802412fb2b7a319e4c61
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2508186
Auto-Submit: Zentaro Kavanagh <zentaro@chromium.org>
Commit-Queue: Corentin Wallez <cwallez@chromium.org>
Reviewed-by: Corentin Wallez <cwallez@chromium.org>
Cr-Commit-Position: refs/heads/master@{#822583}

gpu/command_buffer/client/raster_implementation.cc

@@ -135,7 +135,7 @@ class ScopedSharedMemoryPtr {
 }  // namespace
 
 // Helper to copy data to the GPU service over the transfer cache.
-class RasterImplementation::TransferCacheSerializeHelperImpl
+class RasterImplementation::TransferCacheSerializeHelperImpl final
     : public cc::TransferCacheSerializeHelper {
  public:
   explicit TransferCacheSerializeHelperImpl(RasterImplementation* ri)

gpu/command_buffer/service/copy_texture_chromium_mock.h

@@ -13,7 +13,8 @@
 namespace gpu {
 namespace gles2 {
 
-class MockCopyTexImageResourceManager : public CopyTexImageResourceManager {
+class MockCopyTexImageResourceManager final
+    : public CopyTexImageResourceManager {
  public:
   MockCopyTexImageResourceManager(const gles2::FeatureInfo* feature_info);
   ~MockCopyTexImageResourceManager() final;
@@ -60,7 +61,7 @@ class MockCopyTexImageResourceManager : public CopyTexImageResourceManager {
   DISALLOW_COPY_AND_ASSIGN(MockCopyTexImageResourceManager);
 };
 
-class MockCopyTextureResourceManager
+class MockCopyTextureResourceManager final
     : public CopyTextureCHROMIUMResourceManager {
  public:
   MockCopyTextureResourceManager();