Updates to skimage tool to use it for testing.

src/images/SkImageDecoder.cpp

Index: src/images/SkImageDecoder.cpp
diff --git a/src/images/SkImageDecoder.cpp b/src/images/SkImageDecoder.cpp
index c16efcf1f32797330cf39d29d10ed2da2f5ee951..10721f48dc8d6a70a9d3685423ded83cecf9f547 100644
--- a/src/images/SkImageDecoder.cpp
+++ b/src/images/SkImageDecoder.cpp
@@ -60,7 +60,7 @@ SkImageDecoder::Format SkImageDecoder::getFormat() const {
 }
 
 const char* SkImageDecoder::getFormatName() const {
-    SkASSERT(SK_ARRAY_COUNT(sFormatName) == kLastKnownFormat);
+    SkASSERT(SK_ARRAY_COUNT(sFormatName) == kLastKnownFormat + 1);

[epoger, 2013/04/19 21:35:16]

It scares me that the previous error wasn't caught by a unit test.  Are there
some unit tests that can be beefed up?

[scroggo, 2013/04/19 22:12:01]

Lucky for us, no one was calling it...

Using the switch statement, this assert has been removed.

[epoger, 2013/04/23 16:03:40]

Regarding unit tests: Regardless of whether code is run as part of the Skia
library, or used as a tool to test the Skia library, I think it's good (in the
absence of counter-argument) to make sure it's tested.  Broken tools can cause
all sorts of problems.

     return sFormatName[this->getFormat()];
 }