Revert of Extract most of the mutable state of SkShader into a separate Context object.

src/core/SkBitmapProcState.cpp

Index: src/core/SkBitmapProcState.cpp
diff --git a/src/core/SkBitmapProcState.cpp b/src/core/SkBitmapProcState.cpp
index eecfbbcc483c67e42e99c3dfd85bd8b9e2855b7b..be87d832fdb3fbc30b593a960f0212b714e6ca58 100644
--- a/src/core/SkBitmapProcState.cpp
+++ b/src/core/SkBitmapProcState.cpp
@@ -360,6 +360,17 @@
     return true;
 }
 
+void SkBitmapProcState::endContext() {
+    SkDELETE(fBitmapFilter);
+    fBitmapFilter = NULL;
+    fScaledBitmap.reset();
+
+    if (fScaledCacheID) {
+        SkScaledImageCache::Unlock(fScaledCacheID);
+        fScaledCacheID = NULL;
+    }
+}
+
 SkBitmapProcState::~SkBitmapProcState() {
     if (fScaledCacheID) {
         SkScaledImageCache::Unlock(fScaledCacheID);
@@ -388,7 +399,6 @@
     }
     // The above logic should have always assigned fBitmap, but in case it
     // didn't, we check for that now...
-    // TODO(dominikg): Ask humper@ if we can just use an SkASSERT(fBitmap)?
     if (NULL == fBitmap) {
         return false;
     }
@@ -477,7 +487,6 @@
     // shader will perform.
 
     fMatrixProc = this->chooseMatrixProc(trivialMatrix);
-    // TODO(dominikg): SkASSERT(fMatrixProc) instead? chooseMatrixProc never returns NULL.
     if (NULL == fMatrixProc) {
         return false;
     }
@@ -519,7 +528,6 @@
                 fPaintPMColor = SkPreMultiplyColor(paint.getColor());
                 break;
             default:
-                // TODO(dominikg): Should we ever get here? SkASSERT(false) instead?
                 return false;
         }