[base] Fix undefined behaviour in LazyInstanceImpl.

Patch from Thomas Köppe <tkoeppe@google.com>.

Change-Id: I7ae2e001b6bd72ad67baad64d35e7c17d4ed4716
Reviewed-on: https://chromium-review.googlesource.com/806221Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Commit-Queue: Ulan Degenbaev <ulan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#49838}

src/base/lazy-instance.h

@@ -168,17 +168,13 @@ struct LazyInstanceImpl {
   typedef typename AllocationTrait::StorageType StorageType;
 
  private:
-  static void InitInstance(StorageType* storage) {
-    AllocationTrait::template InitStorageUsingTrait<CreateTrait>(storage);
+  static void InitInstance(void* storage) {
+    AllocationTrait::template InitStorageUsingTrait<CreateTrait>(
+        static_cast<StorageType*>(storage));
   }
 
   void Init() const {
-    InitOnceTrait::Init(
-        &once_,
-        // Casts to void* are needed here to avoid breaking strict aliasing
-        // rules.
-        reinterpret_cast<void(*)(void*)>(&InitInstance),  // NOLINT
-        reinterpret_cast<void*>(&storage_));
+    InitOnceTrait::Init(&once_, &InitInstance, static_cast<void*>(&storage_));
   }
 
  public: