Make SkAndroidCodec support wbmp

dm/DM.cpp

Index: dm/DM.cpp
diff --git a/dm/DM.cpp b/dm/DM.cpp
index 403252b03d7e3d205d086df4dc5839dc6dd99fbc..5fd03174787e3d676f54d7fbb54599c7438cf212 100644
--- a/dm/DM.cpp
+++ b/dm/DM.cpp
@@ -344,20 +344,29 @@ static void push_codec_srcs(Path path) {
         }
     }
 
+    uint32_t numAndroidModes = 0;
     // https://bug.skia.org/4428
+    // Only test subsets for these selected image types.

[scroggo, 2015/11/16 15:19:58]

nit: This sentence is ambiguous - I read it as meaning that for these image
types, we test subsets, but not full decodes.

     static const char* const exts[] = {
         "jpg", "jpeg", "png", "webp",
         "JPG", "JPEG", "PNG", "WEBP",
     };
-    bool supported = false;
     for (const char* ext : exts) {
         if (path.endsWith(ext)) {
-            supported = true;
+            numAndroidModes = 2;
             break;
         }
     }
-    if (!supported) {
-        return;
+
+    static const char* onlyFullImageExts[] = {
+        "wbmp",
+        "WBMP",
+    };
+    for (const char* ext : onlyFullImageExts) {
+        if (path.endsWith(ext)) {
+            numAndroidModes = 1;
+            break;
+        }
     }
 
     const int sampleSizes[] = { 1, 2, 3, 4, 5, 6, 7, 8 };
@@ -368,9 +377,9 @@ static void push_codec_srcs(Path path) {
     };
 
     for (int sampleSize : sampleSizes) {
-        for (AndroidCodecSrc::Mode mode : androidModes) {
+        for (uint32_t m = 0; m < numAndroidModes; m++) {

[scroggo, 2015/11/16 15:19:58]

Now I think I see why you were tempted to go all the way and turn on subset
decoding - this is messy...

Two thoughts:
1. Testing subsets using SkAndroidCodec is pretty similar to using the BRD test
(which in turn uses SkAndroidCodec). Is there a benefit to having both? Or could
we cut down the androidModes to just kFullImage?
2. If we see value in having both versions of subset tests, do you think the
following is more clear?

// set new booleans "full" and "subset" how you currently set numAndroidModes,
// or possibly use static functions.

if (!full && !subset) {
  return;
}

for (sampleSize : sampleSizes) {
  for (colorType : colorTypes) {
    push_android_codec_src(path, kFullImage, colorType, sampleSize);
    if (subset) {
      push_android_codec_src(path, kDivisor, colorType, sampleSize);
    }
  }
} 

[msarett, 2015/11/16 15:40:57]

I think you could make a good argument for this.  Right now, I'm not sure there
is much benefit to having both tests.  I'm hesitating on deleting this test
because I'm wondering if we might ever want subsets without a
BitmapRegionDecoder.
Yeah I like this better.

             for (uint32_t i = 0; i < numColorTypes; i++) {
-                push_android_codec_src(path, mode, colorTypes[i], sampleSize);
+                push_android_codec_src(path, androidModes[m], colorTypes[i], sampleSize);
             }
         }
     }