Revert "Move headers with no dependencies."

This reverts commit 117842223bd13325b6da26110d80e0590c1a742b.

No good:
https://uberchromegw.corp.google.com/i/client.skia/builders/Mac%20Builder/builds/3465/steps/compile/logs/stdio

BUG=skia:4126

Review URL: https://codereview.chromium.org/1262173002 .
diff --git a/include/gpu/gl/SkGLContext.h b/include/gpu/gl/SkGLContext.h
index ba8506c..3d232e5 100644
--- a/include/gpu/gl/SkGLContext.h
+++ b/include/gpu/gl/SkGLContext.h
@@ -9,7 +9,7 @@
 #define SkGLContext_DEFINED
 
 #include "GrGLInterface.h"
-#include "../private/SkGpuFenceSync.h"
+#include "../../src/gpu/SkGpuFenceSync.h"
 
 /**
  * Create an offscreen opengl context with an RGBA8 / 8bit stencil FBO.
@@ -18,7 +18,7 @@
 
 class SK_API SkGLContext : public SkRefCnt {
 public:
-
+    
 
     ~SkGLContext() override;
 
diff --git a/include/views/SkOSWindow_Win.h b/include/views/SkOSWindow_Win.h
index ccab590..85cfec1 100644
--- a/include/views/SkOSWindow_Win.h
+++ b/include/views/SkOSWindow_Win.h
@@ -10,7 +10,7 @@
 #ifndef SkOSWindow_Win_DEFINED
 #define SkOSWindow_Win_DEFINED
 
-#include "../private/SkFunction.h"
+#include "../../src/core/SkFunction.h"
 #include "../private/SkTHash.h"
 #include "SkWindow.h"
 
diff --git a/include/private/SkFunction.h b/src/core/SkFunction.h
similarity index 100%
rename from include/private/SkFunction.h
rename to src/core/SkFunction.h
diff --git a/include/private/SkPathPriv.h b/src/core/SkPathPriv.h
similarity index 100%
rename from include/private/SkPathPriv.h
rename to src/core/SkPathPriv.h
diff --git a/src/core/SkRecords.h b/src/core/SkRecords.h
index 13332a0..9ab04c9 100644
--- a/src/core/SkRecords.h
+++ b/src/core/SkRecords.h
@@ -8,10 +8,10 @@
 #ifndef SkRecords_DEFINED
 #define SkRecords_DEFINED
 
-#include "../private/SkPathPriv.h"
 #include "SkCanvas.h"
 #include "SkDrawable.h"
 #include "SkMatrix.h"
+#include "SkPathPriv.h"
 #include "SkPicture.h"
 #include "SkRSXform.h"
 #include "SkTextBlob.h"
diff --git a/include/private/SkGpuFenceSync.h b/src/gpu/SkGpuFenceSync.h
similarity index 100%
rename from include/private/SkGpuFenceSync.h
rename to src/gpu/SkGpuFenceSync.h