render_pictures: add --mismatchPath flag

tools/image_expectations.h

Index: tools/image_expectations.h
diff --git a/tools/image_expectations.h b/tools/image_expectations.h
index 09a945a1b013b05e4ed874e36efb29ae009892e5..b7b135d91230b60f65936b99468441af467e6f9d 100644
--- a/tools/image_expectations.h
+++ b/tools/image_expectations.h
@@ -90,12 +90,23 @@ namespace sk_tools {
          * @param sourceName name of the source file that generated this result
          * @param fileName relative path to the image output file on local disk
          * @param digest description of the image's contents
-         * @param tileNumber if not NULL, ptr to tile number
+         * @param tileNumber if not NULL, pointer to tile number
          */
         void add(const char *sourceName, const char *fileName, const ImageDigest &digest,
                  const int *tileNumber=NULL);
 
         /**
+         * Returns true if this test result matches its expectations.
+         * If there are no expectations for this test result, this will return false.
+         *
+         * @param sourceName name of the source file that generated this result
+         * @param digest description of the image's contents
+         * @param tileNumber if not NULL, pointer to tile number
+         */
+        bool matchesExpectation(const char *sourceName, const ImageDigest &digest,
+                                const int *tileNumber=NULL);
+
+        /**
          * Writes the summary (as constructed so far) to a file.
          *
          * @param filename path to write the summary to