Revert "Relocate shaders to own dir"

This reverts commit fabe0b26d05624ce7374f6ca89bd66df6142534e.

Reason for revert: Last android roll failed with "external/skia/src/effects/SkGaussianEdgeShader.h:11:10: fatal error: 'SkShaderBase.h' file not found"

Original change's description:
> Relocate shaders to own dir
> 
> Consolidate all shader impls under src/shaders/.
> 
> Change-Id: I450e37541214704c1ad9e379d9d753b7cc62fac3
> Reviewed-on: https://skia-review.googlesource.com/17927
> Commit-Queue: Florin Malita <fmalita@chromium.org>
> Reviewed-by: Herb Derby <herb@google.com>
> 

TBR=mtklein@google.com,herb@google.com,fmalita@chromium.org,reed@google.com
No-Presubmit: true
No-Tree-Checks: true
No-Try: true

Change-Id: Idbb2b75053969df1dad9d8ce0217cd39189b9ddb
Reviewed-on: https://skia-review.googlesource.com/18020
Reviewed-by: Stan Iliev <stani@google.com>
Commit-Queue: Stan Iliev <stani@google.com>

1 files changed, 41 insertions, 0 deletions

diff --git a/src/core/SkEmptyShader.h b/src/core/SkEmptyShader.h
new file mode 100644
index 0000000000..c1bcfe0957
--- /dev/null
+++ b/src/core/SkEmptyShader.h
@@ -0,0 +1,41 @@
+/*
+ * Copyright 2011 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#ifndef SkEmptyShader_DEFINED
+#define SkEmptyShader_DEFINED
+
+#include "SkShaderBase.h"
+
+// TODO: move this to private, as there is a public factory on SkShader
+
+/**
+ *  \class SkEmptyShader
+ *  A Shader that always draws nothing. Its createContext always returns nullptr.
+ */
+class SK_API SkEmptyShader : public SkShaderBase {
+public:
+    SkEmptyShader() {}
+
+    SK_TO_STRING_OVERRIDE()
+    SK_DECLARE_PUBLIC_FLATTENABLE_DESERIALIZATION_PROCS(SkEmptyShader)
+
+protected:
+    Context* onMakeContext(const ContextRec&, SkArenaAlloc*) const override {
+        return nullptr;
+    }
+
+    void flatten(SkWriteBuffer& buffer) const override {
+        // Do nothing.
+        // We just don't want to fall through to SkShader::flatten(),
+        // which will write data we don't care to serialize or decode.
+    }
+
+private:
+    typedef SkShaderBase INHERITED;
+};
+
+#endif