Re-land "Fix external SkImageFilter caching with clips."

src/core/SkImageFilter.cpp

 /*
  * Copyright 2012 The Android Open Source Project
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkImageFilter.h"
 
 #include "SkBitmap.h"
@@ skipping 104 matching lines @@
         cache->set(this, *result, *offset);
         return true;
     }
     return false;
 }
 
 bool SkImageFilter::filterBounds(const SkIRect& src, const SkMatrix& ctm,
                                  SkIRect* dst) const {
     SkASSERT(&src);
     SkASSERT(dst);
+    if (SkImageFilter::GetExternalCache()) {
+        /*
+         *  When the external cache is active, do not intersect the saveLayer
+         *  bounds with the clip bounds. This is so that the cached result
+         *  is always the full size of the primitive's bounds,
+         *  regardless of the clip active on first draw.
+         */
+        *dst = SkIRect::MakeLargest();
+        return true;
+    }
     return this->onFilterBounds(src, ctm, dst);
 }
 
 void SkImageFilter::computeFastBounds(const SkRect& src, SkRect* dst) const {
     if (0 == fInputCount) {
         *dst = src;
         return;
     }
     if (this->getInput(0)) {
         this->getInput(0)->computeFastBounds(src, dst);
@@ skipping 288 matching lines @@
 
 CacheImpl::~CacheImpl() {
     SkTDynamicHash<Value, Key>::Iter iter(&fData);
 
     while (!iter.done()) {
         Value* v = &*iter;
         ++iter;
         delete v;
     }
 }