Force the debugger to link decoders.

debugger/SkDebugger.cpp

Index: debugger/SkDebugger.cpp
diff --git a/debugger/SkDebugger.cpp b/debugger/SkDebugger.cpp
index 2d13c758d2a335931b972dfaf742054088d45266..cd951444ae9fdb0166191dcfd74ff23ee09bb1d5 100644
--- a/debugger/SkDebugger.cpp
+++ b/debugger/SkDebugger.cpp
@@ -128,3 +128,18 @@ void SkDebugger::getOverviewText(const SkTDArray<double>* typeTimes,
     overview->appendS32(pictureHeight());
     overview->append("px");
 }
+
+#include "SkImageDecoder.h"
+
+void forceLinking();
+void forceLinking() {
+    // This function leaks, but that is okay because it is not intended
+    // to be called. It is only here so that the linker will include the
+    // decoders.
+    SkDEBUGCODE(SkImageDecoder *creator = ) CreateJPEGImageDecoder();
+    SkASSERT(creator);
+#ifdef SK_BUILD_FOR_UNIX
+    SkDEBUGCODE(creator = ) CreateGIFImageDecoder();
+    SkASSERT(creator);
+#endif
+}