Make Fushia TTS PlatformImpl a leaky instance

This CL is making the TtsPlatformImpl instance a leaky
instance since the singleton is alive for the whole
duration of the process.

Bug: 1133813
Change-Id: Iecdf3ea3451308376412d91c3766510364caeaa9
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2441965Reviewed-by: François Doray <fdoray@chromium.org>
Reviewed-by: Dominic Mazzoni <dmazzoni@chromium.org>
Commit-Queue: Etienne Bergeron <etienneb@chromium.org>
Cr-Commit-Position: refs/heads/master@{#813300}

content/browser/speech/tts_fuchsia.cc

@@ -4,6 +4,8 @@
 
 #include "content/browser/speech/tts_platform_impl.h"
 
+#include "base/no_destructor.h"
+
 namespace content {
 
 // Dummy implementation to prevent a browser crash, see crbug.com/1019511
@@ -11,7 +13,8 @@ namespace content {
 class TtsPlatformImplFuchsia : public TtsPlatformImpl {
  public:
   TtsPlatformImplFuchsia() = default;
-  ~TtsPlatformImplFuchsia() override = default;
+  TtsPlatformImplFuchsia(const TtsPlatformImplFuchsia&) = delete;
+  TtsPlatformImplFuchsia& operator=(const TtsPlatformImplFuchsia&) = delete;
 
   // TtsPlatform implementation.
   bool PlatformImplAvailable() override { return false; }
@@ -31,11 +34,9 @@ class TtsPlatformImplFuchsia : public TtsPlatformImpl {
 
   // Get the single instance of this class.
   static TtsPlatformImplFuchsia* GetInstance() {
-    return base::Singleton<TtsPlatformImplFuchsia>::get();
+    static base::NoDestructor<TtsPlatformImplFuchsia> tts_platform;
+    return tts_platform.get();
   }
-
- private:
-  DISALLOW_COPY_AND_ASSIGN(TtsPlatformImplFuchsia);
 };
 
 // static