Use skia discardable memory for decoded images on Android.

Source/platform/graphics/DeferredImageDecoder.cpp

Index: Source/platform/graphics/DeferredImageDecoder.cpp
diff --git a/Source/platform/graphics/DeferredImageDecoder.cpp b/Source/platform/graphics/DeferredImageDecoder.cpp
index abc9f8d929ae10bc1dfe637dd903060f0d4f809e..f01c84dc1df87d7f55c3e9047933cd4a7d0049dd 100644
--- a/Source/platform/graphics/DeferredImageDecoder.cpp
+++ b/Source/platform/graphics/DeferredImageDecoder.cpp
@@ -84,14 +84,11 @@ bool DeferredImageDecoder::isLazyDecoded(const SkBitmap& bitmap)
 void DeferredImageDecoder::setEnabled(bool enabled)
 {
     s_enabled = enabled;
-#if !OS(ANDROID)
-    // FIXME: This code is temporary to enable discardable memory for
-    // non-Android platforms. In the future all platforms will be
-    // the same and we can remove this code.
+    // FIXME: Remove all non-discardable memory related code now that this is
+    // used on all platforms.
     s_skiaDiscardableMemoryEnabled = enabled;
     if (enabled)
         ImageDecodingStore::setImageCachingEnabled(false);
-#endif
 }
 
 bool DeferredImageDecoder::enabled()