Make SkBitmapCache remove invalid bitmaps from the SkResourceCache.

tests/SkResourceCacheTest.cpp

 /*
  * Copyright 2014 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 #include "Test.h"
 #include "SkCanvas.h"
 #include "SkGraphics.h"
 #include "SkBitmapCache.h"
+#include "SkDiscardableMemoryPool.h"
 
 static const int kCanvasSize = 1;
 static const int kBitmapSize = 16;
 static const int kScale = 8;
 
 static bool is_in_scaled_image_cache(const SkBitmap& orig,
                                      SkScalar xScale,
                                      SkScalar yScale) {
     SkBitmap scaled;
     float roundedImageWidth = SkScalarRoundToScalar(orig.width() * xScale);
@@ skipping 81 matching lines @@
     REPORTER_ASSERT(reporter, ! SkBitmapCache::Add(cachedBitmap.getGenerationID(), SkIRect::MakeXYWH(-1, 0, 5, 5), cachedBitmap));
     REPORTER_ASSERT(reporter, ! SkBitmapCache::Find(cachedBitmap.getGenerationID(), rect, &bm));
 
     // Should not be in the cache
     REPORTER_ASSERT(reporter, !SkBitmapCache::Find(cachedBitmap.getGenerationID(), rect, &bm));
 
     REPORTER_ASSERT(reporter, SkBitmapCache::Add(cachedBitmap.getGenerationID(), rect, cachedBitmap));
     // Should be in the cache, we just added it
     REPORTER_ASSERT(reporter, SkBitmapCache::Find(cachedBitmap.getGenerationID(), rect, &bm));
 }
+
+DEF_TEST(BitmapCache_discarded_bitmap, reporter) {
+    SkBitmap bm;
+    SkIRect rect = SkIRect::MakeWH(5, 5);
+    SkBitmap cachedBitmap = createAllocatedBitmap(SkImageInfo::MakeN32Premul(5, 5));
+    cachedBitmap.setImmutable();
+    cachedBitmap.unlockPixels();
+
+    // Add a bitmap to the cache.
+    REPORTER_ASSERT(reporter, SkBitmapCache::Add(cachedBitmap.getGenerationID(), rect, cachedBitmap));
+    REPORTER_ASSERT(reporter, SkBitmapCache::Find(cachedBitmap.getGenerationID(), rect, &bm));
+
+    // Finding more than once works fine.
+    REPORTER_ASSERT(reporter, SkBitmapCache::Find(cachedBitmap.getGenerationID(), rect, &bm));
+    bm.unlockPixels();
+
+    // Drop the pixels in the bitmap.
+    REPORTER_ASSERT(reporter, SkGetGlobalDiscardableMemoryPool()->getRAMUsed() > 0);
+    SkGetGlobalDiscardableMemoryPool()->dumpPool();
+    REPORTER_ASSERT(reporter, SkGetGlobalDiscardableMemoryPool()->getRAMUsed() == 0);
+
+    // The bitmap is not in the cache since it has been dropped.
+    REPORTER_ASSERT(reporter, !SkBitmapCache::Find(cachedBitmap.getGenerationID(), rect, &bm));
+
+    cachedBitmap = createAllocatedBitmap(SkImageInfo::MakeN32Premul(5, 5));
+    cachedBitmap.setImmutable();
+    cachedBitmap.unlockPixels();
+
+    // We can add the bitmap back to the cache and find it again.
+    REPORTER_ASSERT(reporter, SkBitmapCache::Add(cachedBitmap.getGenerationID(), rect, cachedBitmap));
+    REPORTER_ASSERT(reporter, SkBitmapCache::Find(cachedBitmap.getGenerationID(), rect, &bm));
+}
 #endif