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/SkMagnifierImageFilter.cpp b/src/effects/SkMagnifierImageFilter.cpp
index 5096640..51ade99 100644
--- a/src/effects/SkMagnifierImageFilter.cpp
+++ b/src/effects/SkMagnifierImageFilter.cpp
@@ -282,11 +282,11 @@
 bool SkMagnifierImageFilter::onFilterImage(Proxy*, const SkBitmap& src,
                                            const Context&, SkBitmap* dst,
                                            SkIPoint* offset) const {
-    SkASSERT(src.colorType() == kN32_SkColorType);
+    SkASSERT(src.colorType() == kPMColor_SkColorType);
     SkASSERT(fSrcRect.width() < src.width());
     SkASSERT(fSrcRect.height() < src.height());
 
-    if ((src.colorType() != kN32_SkColorType) ||
+    if ((src.colorType() != kPMColor_SkColorType) ||
         (fSrcRect.width() >= src.width()) ||
         (fSrcRect.height() >= src.height())) {
       return false;