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

gm/gmmain.cpp

Index: gm/gmmain.cpp
===================================================================
--- gm/gmmain.cpp	(revision 9077)
+++ gm/gmmain.cpp	(working copy)
@@ -607,7 +607,7 @@
             (gRec.fBackend == kPDF_Backend && CAN_IMAGE_PDF)) {
 
             path = make_filename(writePath, renderModeDescriptor, name.c_str(),
-                                 "png");
+                                 kPNG_FileExtension);
             success = write_bitmap(path, bitmap);
         }
         if (kPDF_Backend == gRec.fBackend) {
@@ -727,6 +727,8 @@
         }
         SkString completeNameString = baseNameString;
         completeNameString.append(renderModeDescriptor);
+        completeNameString.append(".");
+        completeNameString.append(kPNG_FileExtension);
         const char* completeName = completeNameString.c_str();
 
         if (expectations.empty()) {
@@ -746,7 +748,7 @@
             if (fMismatchPath) {
                 SkString path =
                     make_filename(fMismatchPath, renderModeDescriptor,
-                                  baseNameString.c_str(), "png");
+                                  baseNameString.c_str(), kPNG_FileExtension);
                 write_bitmap(path, actualBitmap);
             }
 
@@ -865,7 +867,10 @@
             if (!SkBitmapHasher::ComputeDigest(actualBitmap, &actualBitmapHash)) {
                 actualBitmapHash = 0;
             }
-            add_actual_results_to_json_summary(name.c_str(), actualBitmapHash,
+            SkString nameWithExtension(name);
+            nameWithExtension.append(".");
+            nameWithExtension.append(kPNG_FileExtension);
+            add_actual_results_to_json_summary(nameWithExtension.c_str(), actualBitmapHash,
                                                ErrorCombination(kMissingExpectations_ErrorType),
                                                false);
             RecordTestResults(ErrorCombination(kMissingExpectations_ErrorType), name, "");