Remove SkImageGenerator pieces only for SkCodec.

Follow up to the split between SkImageGenerator and SkCodec. Now that
SkCodec does not inherit from SkImageGenerator, SkImageGenerator no
longer needs Options or Result, which were added for SkCodec. Remove
them, but keep them behind a flag, since Chromium has its own
subclasses of SkImageGenerator which assume the old signature for
onGetPixels.

Review URL: https://codereview.chromium.org/1226023003
diff --git a/tests/CachedDecodingPixelRefTest.cpp b/tests/CachedDecodingPixelRefTest.cpp
index 465b69b..a2032ba 100644
--- a/tests/CachedDecodingPixelRefTest.cpp
+++ b/tests/CachedDecodingPixelRefTest.cpp
@@ -182,16 +182,29 @@
                                     kOpaque_SkAlphaType);
     }
 
-    virtual Result onGetPixels(const SkImageInfo& info, void* pixels, size_t rowBytes,
-                               const Options&,
-                               SkPMColor ctable[], int* ctableCount) override {
+#ifdef SK_LEGACY_IMAGE_GENERATOR_ENUMS_AND_OPTIONS
+    Result onGetPixels(const SkImageInfo& info, void* pixels, size_t rowBytes,
+                       const Options&,
+                       SkPMColor ctable[], int* ctableCount) override {
+#else
+    bool onGetPixels(const SkImageInfo& info, void* pixels, size_t rowBytes,
+                     SkPMColor ctable[], int* ctableCount) override {
+#endif
         REPORTER_ASSERT(fReporter, pixels != NULL);
         REPORTER_ASSERT(fReporter, rowBytes >= info.minRowBytes());
         if (fType != kSucceedGetPixels_TestType) {
+#ifdef SK_LEGACY_IMAGE_GENERATOR_ENUMS_AND_OPTIONS
             return kUnimplemented;
+#else
+            return false;
+#endif
         }
         if (info.colorType() != kN32_SkColorType) {
+#ifdef SK_LEGACY_IMAGE_GENERATOR_ENUMS_AND_OPTIONS
             return kInvalidConversion;
+#else
+            return false;
+#endif
         }
         char* bytePtr = static_cast<char*>(pixels);
         for (int y = 0; y < info.height(); ++y) {
@@ -199,7 +212,11 @@
                         TestImageGenerator::Color(), info.width());
             bytePtr += rowBytes;
         }
+#ifdef SK_LEGACY_IMAGE_GENERATOR_ENUMS_AND_OPTIONS
         return kSuccess;
+#else
+        return true;
+#endif
     }
 
 private: