Cleanup SkImageGenerator, add missing fns to GrBackendTextureImageGenerator

No "real" API changes.
TBR=reed@google.com

Bug: skia:
Change-Id: I08c29f76806388394938f204f2a50b2fd6ea8942
Reviewed-on: https://skia-review.googlesource.com/16662
Reviewed-by: Brian Osman <brianosman@google.com>
Reviewed-by: Matt Sarett <msarett@google.com>
Commit-Queue: Brian Osman <brianosman@google.com>
diff --git a/include/core/SkImageGenerator.h b/include/core/SkImageGenerator.h
index 3e433a3..8e875da 100644
--- a/include/core/SkImageGenerator.h
+++ b/include/core/SkImageGenerator.h
@@ -169,19 +169,14 @@
 
     SkImageGenerator(const SkImageInfo& info, uint32_t uniqueId = kNeedNewImageUniqueID);
 
-    virtual SkData* onRefEncodedData();
+    virtual SkData* onRefEncodedData() { return nullptr; }
 
-    virtual bool onGetPixels(const SkImageInfo& info, void* pixels, size_t rowBytes,
-                             SkPMColor ctable[], int* ctableCount);
+    virtual bool onGetPixels(const SkImageInfo&, void*, size_t, SkPMColor[], int*) { return false; }
 
-    virtual bool onIsValid(GrContext*) const;
+    virtual bool onIsValid(GrContext*) const { return true; }
 
-    virtual bool onQueryYUV8(SkYUVSizeInfo*, SkYUVColorSpace*) const {
-        return false;
-    }
-    virtual bool onGetYUV8Planes(const SkYUVSizeInfo&, void*[3] /*planes*/) {
-        return false;
-    }
+    virtual bool onQueryYUV8(SkYUVSizeInfo*, SkYUVColorSpace*) const { return false; }
+    virtual bool onGetYUV8Planes(const SkYUVSizeInfo&, void*[3] /*planes*/) { return false; }
 
     struct Options {
         Options()
diff --git a/src/core/SkImageGenerator.cpp b/src/core/SkImageGenerator.cpp
index fe9bb00..35eaf89 100644
--- a/src/core/SkImageGenerator.cpp
+++ b/src/core/SkImageGenerator.cpp
@@ -104,21 +104,6 @@
 }
 #endif
 
-/////////////////////////////////////////////////////////////////////////////////////////////
-
-SkData* SkImageGenerator::onRefEncodedData() {
-    return nullptr;
-}
-
-bool SkImageGenerator::onGetPixels(const SkImageInfo& info, void* dst, size_t rb,
-                                   SkPMColor* colors, int* colorCount) {
-    return false;
-}
-
-bool SkImageGenerator::onIsValid(GrContext*) const {
-    return true;
-}
-
 ///////////////////////////////////////////////////////////////////////////////////////////////////
 
 #include "SkBitmap.h"
diff --git a/src/gpu/GrBackendTextureImageGenerator.cpp b/src/gpu/GrBackendTextureImageGenerator.cpp
index d92b32f..da9fe69 100644
--- a/src/gpu/GrBackendTextureImageGenerator.cpp
+++ b/src/gpu/GrBackendTextureImageGenerator.cpp
@@ -89,20 +89,6 @@
     fRefHelper->unref();
 }
 
-bool GrBackendTextureImageGenerator::onGetPixels(const SkImageInfo& info, void* pixels,
-                                                 size_t rowBytes, SkPMColor ctable[],
-                                                 int* ctableCount) {
-    // TODO: Is there any way to implement this? I don't think so.
-    return false;
-}
-
-bool GrBackendTextureImageGenerator::onGetPixels(const SkImageInfo& info, void* pixels,
-                                                 size_t rowBytes, const Options& opts) {
-
-    // TODO: Is there any way to implement this? I don't think so.
-    return false;
-}
-
 ///////////////////////////////////////////////////////////////////////////////////////////////////
 
 #if SK_SUPPORT_GPU
diff --git a/src/gpu/GrBackendTextureImageGenerator.h b/src/gpu/GrBackendTextureImageGenerator.h
index 2f35895..1a316d1 100644
--- a/src/gpu/GrBackendTextureImageGenerator.h
+++ b/src/gpu/GrBackendTextureImageGenerator.h
@@ -22,12 +22,12 @@
     ~GrBackendTextureImageGenerator();
 
 protected:
-    bool onGetPixels(const SkImageInfo& info, void* pixels, size_t rowBytes, SkPMColor ctable[],
-                     int* ctableCount) override;
-    bool onGetPixels(const SkImageInfo& info, void* pixels, size_t rowBytes, const Options& opts)
-                     override;
+    // NOTE: We would like to validate that the owning context hasn't been abandoned, but we can't
+    // do that safely (we might be on another thread). So assume everything is fine.
+    bool onIsValid(GrContext*) const override { return true; }
 
 #if SK_SUPPORT_GPU
+    bool onCanGenerateTexture() const override { return true; }
     sk_sp<GrTextureProxy> onGenerateTexture(GrContext*, const SkImageInfo&,
                                             const SkIPoint&) override;
 #endif