SampleApp - reduce unnecessary verbosity [with --picture $path]

Before this change, `SampleApp --picture $path` prints out usage (as
well as --pictureDir) as if there was a syntax error in the command
line arguments.

BUG=skia:1677
R=reed@google.com

Review URL: https://codereview.chromium.org/24503003

git-svn-id: http://skia.googlecode.com/svn/trunk@11748 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/samplecode/SampleApp.cpp b/samplecode/SampleApp.cpp
index f303794..f044e70 100644
--- a/samplecode/SampleApp.cpp
+++ b/samplecode/SampleApp.cpp
@@ -790,6 +790,10 @@
             }
         } else if (strcmp(*argv, "--list") == 0) {
             listTitles();
+        } else if (strcmp(*argv, "--pictureDir") == 0) {
+            ++argv;  // This case is dealt with in registerPictFileSamples().
+        } else if (strcmp(*argv, "--picture") == 0) {
+            ++argv;  // This case is dealt with in registerPictFileSample().
         }
         else {
             usage(commandName);