Revert of Add a mutex to GrContext::readSurfacePixels to protect against multiple CPU raster threads accessin…

include/gpu/GrContext.h

Index: include/gpu/GrContext.h
diff --git a/include/gpu/GrContext.h b/include/gpu/GrContext.h
index dcff3063b269ff198e16598c9aa9664c84a88f9f..7f1e4109fad9564e65fa6acbc25266d295878a3b 100644
--- a/include/gpu/GrContext.h
+++ b/include/gpu/GrContext.h
@@ -15,7 +15,6 @@
 #include "GrRenderTarget.h"
 #include "GrTextureProvider.h"
 #include "SkMatrix.h"
-#include "SkMutex.h"
 #include "SkPathEffect.h"
 #include "SkTypes.h"
 
@@ -381,11 +380,6 @@
     bool                            fDidTestPMConversions;
     int                             fPMToUPMConversion;
     int                             fUPMToPMConversion;
-    // The sw backend may call GrContext::readSurfacePixels on multiple threads
-    // We may transfer the responsibilty for using a mutex to the sw backend
-    // when there are fewer code paths that lead to a readSurfacePixels call
-    // from the sw backend.
-    SkMutex                         fReadPixelsMutex;
 
     struct CleanUpData {
         PFCleanUpFunc fFunc;