Revert of Modernize SkMutex and SkSemaphore. (patchset #2 id:20001 of https://codereview.chromium.org/1947153002/ )

Reason for revert:
This CL seems to have broken the Linux x64 and Mac
bots, e.g.

https://build.chromium.org/p/chromium/builders/Linux%20x64/builds/19052
https://build.chromium.org/p/chromium/builders/Mac/builds/15151

The error appears to have something to do with new static initializers being
added.

Original issue's description:
> Modernize SkMutex and SkSemaphore.
>
>    - use <atomic>
>    - fuse SkMutex and SkBaseMutex
>    - fuse SkSemaphore and SkBaseSemaphore
>
> Still TODO:
>    - replace SK_DECLARE_STATIC_MUTEX(name) with static SkMutex name
>
> I just didn't want to bother fixing all that up until I know this CL sticks.
>
> BUG=skia:
> GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1947153002
>
> No public API changes.
> TBR=reed@google.com
>
> Committed: https://skia.googlesource.com/skia/+/427c2819d9237d7d7729c59238036cfc73c072ea

TBR=herb@google.com,mtklein@chromium.org,reed@google.com,bsalomon@google.com
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=609340

Review-Url: https://codereview.chromium.org/1945343003
diff --git a/src/lazy/SkDiscardableMemoryPool.cpp b/src/lazy/SkDiscardableMemoryPool.cpp
index 2be4c75..1f3bcf9 100644
--- a/src/lazy/SkDiscardableMemoryPool.cpp
+++ b/src/lazy/SkDiscardableMemoryPool.cpp
@@ -29,7 +29,7 @@
     /**
      *  Without mutex, will be not be thread safe.
      */
-    DiscardableMemoryPool(size_t budget, SkMutex* mutex = nullptr);
+    DiscardableMemoryPool(size_t budget, SkBaseMutex* mutex = nullptr);
     virtual ~DiscardableMemoryPool();
 
     SkDiscardableMemory* create(size_t bytes) override;
@@ -52,9 +52,9 @@
     #endif  // SK_LAZY_CACHE_STATS
 
 private:
-    SkMutex* fMutex;
-    size_t   fBudget;
-    size_t   fUsed;
+    SkBaseMutex* fMutex;
+    size_t       fBudget;
+    size_t       fUsed;
     SkTInternalLList<PoolDiscardableMemory> fList;
 
     /** Function called to free memory if needed */
@@ -128,7 +128,8 @@
 
 ////////////////////////////////////////////////////////////////////////////////
 
-DiscardableMemoryPool::DiscardableMemoryPool(size_t budget, SkMutex* mutex)
+DiscardableMemoryPool::DiscardableMemoryPool(size_t budget,
+                                             SkBaseMutex* mutex)
     : fMutex(mutex)
     , fBudget(budget)
     , fUsed(0) {
@@ -240,7 +241,7 @@
 
 }  // namespace
 
-SkDiscardableMemoryPool* SkDiscardableMemoryPool::Create(size_t size, SkMutex* mutex) {
+SkDiscardableMemoryPool* SkDiscardableMemoryPool::Create(size_t size, SkBaseMutex* mutex) {
     return new DiscardableMemoryPool(size, mutex);
 }