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/src/effects/SkTransparentShader.cpp b/src/effects/SkTransparentShader.cpp
index bd8b99a..b6a5e1e 100644
--- a/src/effects/SkTransparentShader.cpp
+++ b/src/effects/SkTransparentShader.cpp
@@ -29,7 +29,7 @@
             if (fAlpha == 255)
                 flags |= kOpaqueAlpha_Flag;
             break;
-        case kN32_SkColorType:
+        case kPMColor_SkColorType:
             if (fAlpha == 255 && fDevice->isOpaque())
                 flags |= kOpaqueAlpha_Flag;
             break;
@@ -43,7 +43,7 @@
     unsigned scale = SkAlpha255To256(fAlpha);
 
     switch (fDevice->colorType()) {
-        case kN32_SkColorType:
+        case kPMColor_SkColorType:
             if (scale == 256) {
                 SkPMColor* src = fDevice->getAddr32(x, y);
                 if (src != span) {