diff -r 000000000000 -r 6474c204b198 gfx/skia/trunk/src/effects/gradients/SkBitmapCache.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/gfx/skia/trunk/src/effects/gradients/SkBitmapCache.cpp	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,153 @@
+
+/*
+ * Copyright 2010 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+
+#include "SkBitmapCache.h"
+
+struct SkBitmapCache::Entry {
+    Entry*      fPrev;
+    Entry*      fNext;
+
+    void*       fBuffer;
+    size_t      fSize;
+    SkBitmap    fBitmap;
+
+    Entry(const void* buffer, size_t size, const SkBitmap& bm)
+            : fPrev(NULL),
+              fNext(NULL),
+              fBitmap(bm) {
+        fBuffer = sk_malloc_throw(size);
+        fSize = size;
+        memcpy(fBuffer, buffer, size);
+    }
+
+    ~Entry() { sk_free(fBuffer); }
+
+    bool equals(const void* buffer, size_t size) const {
+        return (fSize == size) && !memcmp(fBuffer, buffer, size);
+    }
+};
+
+SkBitmapCache::SkBitmapCache(int max) : fMaxEntries(max) {
+    fEntryCount = 0;
+    fHead = fTail = NULL;
+
+    this->validate();
+}
+
+SkBitmapCache::~SkBitmapCache() {
+    this->validate();
+
+    Entry* entry = fHead;
+    while (entry) {
+        Entry* next = entry->fNext;
+        delete entry;
+        entry = next;
+    }
+}
+
+SkBitmapCache::Entry* SkBitmapCache::detach(Entry* entry) const {
+    if (entry->fPrev) {
+        SkASSERT(fHead != entry);
+        entry->fPrev->fNext = entry->fNext;
+    } else {
+        SkASSERT(fHead == entry);
+        fHead = entry->fNext;
+    }
+    if (entry->fNext) {
+        SkASSERT(fTail != entry);
+        entry->fNext->fPrev = entry->fPrev;
+    } else {
+        SkASSERT(fTail == entry);
+        fTail = entry->fPrev;
+    }
+    return entry;
+}
+
+void SkBitmapCache::attachToHead(Entry* entry) const {
+    entry->fPrev = NULL;
+    entry->fNext = fHead;
+    if (fHead) {
+        fHead->fPrev = entry;
+    } else {
+        fTail = entry;
+    }
+    fHead = entry;
+}
+
+bool SkBitmapCache::find(const void* buffer, size_t size, SkBitmap* bm) const {
+    AutoValidate av(this);
+
+    Entry* entry = fHead;
+    while (entry) {
+        if (entry->equals(buffer, size)) {
+            if (bm) {
+                *bm = entry->fBitmap;
+            }
+            // move to the head of our list, so we purge it last
+            this->detach(entry);
+            this->attachToHead(entry);
+            return true;
+        }
+        entry = entry->fNext;
+    }
+    return false;
+}
+
+void SkBitmapCache::add(const void* buffer, size_t len, const SkBitmap& bm) {
+    AutoValidate av(this);
+
+    if (fEntryCount == fMaxEntries) {
+        SkASSERT(fTail);
+        delete this->detach(fTail);
+        fEntryCount -= 1;
+    }
+
+    Entry* entry = SkNEW_ARGS(Entry, (buffer, len, bm));
+    this->attachToHead(entry);
+    fEntryCount += 1;
+}
+
+///////////////////////////////////////////////////////////////////////////////
+
+#ifdef SK_DEBUG
+
+void SkBitmapCache::validate() const {
+    SkASSERT(fEntryCount >= 0 && fEntryCount <= fMaxEntries);
+
+    if (fEntryCount > 0) {
+        SkASSERT(NULL == fHead->fPrev);
+        SkASSERT(NULL == fTail->fNext);
+
+        if (fEntryCount == 1) {
+            SkASSERT(fHead == fTail);
+        } else {
+            SkASSERT(fHead != fTail);
+        }
+
+        Entry* entry = fHead;
+        int count = 0;
+        while (entry) {
+            count += 1;
+            entry = entry->fNext;
+        }
+        SkASSERT(count == fEntryCount);
+
+        entry = fTail;
+        while (entry) {
+            count -= 1;
+            entry = entry->fPrev;
+        }
+        SkASSERT(0 == count);
+    } else {
+        SkASSERT(NULL == fHead);
+        SkASSERT(NULL == fTail);
+    }
+}
+
+#endif