Revert of Rename kPMColor_SkColorType to kN32_SkColorType. (https://codereview.chromium.org/227433009/)

Reason for revert:
Chrome's side of define changes not easy to figure out quickly. Reverting this for DEPS roll for now.

Original issue's description:
> Rename kPMColor_SkColorType to kN32_SkColorType.
>
> The new name better represents what this flag means.
>
> BUG=skia:2384
>
> Committed: http://code.google.com/p/skia/source/detail?r=14117

R=reed@google.com, scroggo@google.com
TBR=reed@google.com, scroggo@google.com
NOTREECHECKS=true
NOTRY=true
BUG=skia:2384

Author: bensong@google.com

Review URL: https://codereview.chromium.org/234833003

git-svn-id: http://skia.googlecode.com/svn/trunk@14149 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/gm/gmmain.cpp b/gm/gmmain.cpp
index 03556e7..52e7332 100644
--- a/gm/gmmain.cpp
+++ b/gm/gmmain.cpp
@@ -268,7 +268,7 @@
     static void force_all_opaque(const SkBitmap& bitmap) {
         SkColorType colorType = bitmap.colorType();
         switch (colorType) {
-        case kN32_SkColorType:
+        case kPMColor_SkColorType:
             force_all_opaque_8888(bitmap);
             break;
         case kRGB_565_SkColorType:
@@ -294,7 +294,7 @@
         // from this method, we should be able to get rid of the
         // transformation to 8888 format also.
         SkBitmap copy;
-        bitmap.copyTo(&copy, kN32_SkColorType);
+        bitmap.copyTo(&copy, kPMColor_SkColorType);
         if (!SkImageEncoder::EncodeFile(path.c_str(), copy,
                                         SkImageEncoder::kPNG_Type,
                                         100)) {
@@ -740,8 +740,8 @@
             return;
         }
 
-        if ((kN32_SkColorType != expectedBitmap.colorType()) ||
-            (kN32_SkColorType != actualBitmap.colorType())) {
+        if ((kPMColor_SkColorType != expectedBitmap.colorType()) ||
+            (kPMColor_SkColorType != actualBitmap.colorType())) {
             SkDebugf("---- %s: not computing max per-channel pixel mismatch because non-8888\n",
                      testName);
             return;