Revert of Remove SkThread.h, include SkMutex.h or SkAtomics.h as appropriate.

src/core/SkImageFilter.cpp

Index: src/core/SkImageFilter.cpp
diff --git a/src/core/SkImageFilter.cpp b/src/core/SkImageFilter.cpp
index 394d8b20e77023fea6149b854ba57b54d93c19a0..7233ec670698d1ebacc80dc95d664bb38e4cd40e 100644
--- a/src/core/SkImageFilter.cpp
+++ b/src/core/SkImageFilter.cpp
@@ -13,13 +13,12 @@
 #include "SkDevice.h"
 #include "SkLazyPtr.h"
 #include "SkMatrixImageFilter.h"
-#include "SkMutex.h"
 #include "SkReadBuffer.h"
+#include "SkWriteBuffer.h"
 #include "SkRect.h"
 #include "SkTDynamicHash.h"
 #include "SkTInternalLList.h"
 #include "SkValidationUtils.h"
-#include "SkWriteBuffer.h"
 #if SK_SUPPORT_GPU
 #include "GrContext.h"
 #include "GrDrawContext.h"
@@ -29,9 +28,9 @@
 
 #ifdef SK_BUILD_FOR_IOS
   enum { kDefaultCacheSize = 2 * 1024 * 1024 };
-#else
+#else 
   enum { kDefaultCacheSize = 128 * 1024 * 1024 };
-#endif
+#endif 
 
 static int32_t next_image_filter_unique_id() {
     static int32_t gImageFilterUniqueID;
@@ -547,4 +546,4 @@
                                        SkBitmap* result, SkIPoint* offset) {
     return fDevice->filterImage(filter, src, ctx, result, offset);
 }
-
+