GM: include filename extension (.png) of each output file in JSON summary

gm/gm_expectations.cpp

Index: gm/gm_expectations.cpp
===================================================================
--- gm/gm_expectations.cpp	(revision 9077)
+++ gm/gm_expectations.cpp	(working copy)
@@ -162,8 +162,7 @@
     // IndividualImageExpectationsSource class...
 
     Expectations IndividualImageExpectationsSource::get(const char *testName) {
-        SkString path = make_filename(fRootDir.c_str(), "", testName,
-                                      "png");
+        SkString path = make_filename(fRootDir.c_str(), "", testName, kPNG_FileExtension);
         SkBitmap referenceBitmap;
         bool decodedReferenceBitmap =
             SkImageDecoder::DecodeFile(path.c_str(), &referenceBitmap,
@@ -186,7 +185,10 @@
     }
 
     Expectations JsonExpectationsSource::get(const char *testName) {
-        return Expectations(fJsonExpectedResults[testName]);
+        SkString testNameWithExtension(testName);
+        testNameWithExtension.append(".");
+        testNameWithExtension.append(kPNG_FileExtension);
+        return Expectations(fJsonExpectedResults[testNameWithExtension.c_str()]);
     }
 
     /*static*/ SkData* JsonExpectationsSource::ReadIntoSkData(SkStream &stream, size_t maxBytes) {