Integrate r128344 and r128253 from WebKit

cc/CCPrioritizedTextureManager.h

Index: cc/CCPrioritizedTextureManager.h
diff --git a/cc/CCPrioritizedTextureManager.h b/cc/CCPrioritizedTextureManager.h
index 15bdc186acc275231862157a806b0478f3549ba9..52b35d68d2b4696100cf9e74c19693b05392af7c 100644
--- a/cc/CCPrioritizedTextureManager.h
+++ b/cc/CCPrioritizedTextureManager.h
@@ -33,6 +33,8 @@ public:
     }
     ~CCPrioritizedTextureManager();
 
+    typedef Vector<CCPrioritizedTexture::Backing*> BackingVector;
+
     // FIXME (http://crbug.com/137094): This 64MB default is a straggler from the
     // old texture manager and is just to give us a default memory allocation before
     // we get a callback from the GPU memory manager. We should probaby either:
@@ -54,12 +56,18 @@ public:
     void prioritizeTextures();
     void clearPriorities();
 
+    void reduceMemoryOnImplThread(size_t limitBytes, CCResourceProvider*);
+    void getEvictedBackings(BackingVector& evictedBackings);
+    void unlinkEvictedBackings(const BackingVector& evictedBackings);
+    // Deletes all evicted backings, unlinking them from their owning textures if needed.
+    // Returns true if this function to unlinked any backings from their owning texture while
+    // destroying them.
+    bool deleteEvictedBackings();
+
     bool requestLate(CCPrioritizedTexture*);
 
     void reduceMemory(CCResourceProvider*);
     void clearAllMemory(CCResourceProvider*);
-    void unlinkAllBackings();
-    void deleteAllUnlinkedBackings();
 
     void acquireBackingTextureIfNeeded(CCPrioritizedTexture*, CCResourceProvider*);
 
@@ -67,11 +75,14 @@ public:
     void unregisterTexture(CCPrioritizedTexture*);
     void returnBackingTexture(CCPrioritizedTexture*);
 
-#if !ASSERT_DISABLED
-    void assertInvariants();
-#endif
-
 private:
+    friend class CCPrioritizedTextureTest;
+
+    enum EvictionPriorityPolicy {
+        RespectManagerPriorityCutoff,
+        DoNotRespectManagerPriorityCutoff,
+    };
+
     // Compare textures. Highest priority first.
     static inline bool compareTextures(CCPrioritizedTexture* a, CCPrioritizedTexture* b)
     {
@@ -82,19 +93,29 @@ private:
     // Compare backings. Lowest priority first.
     static inline bool compareBackings(CCPrioritizedTexture::Backing* a, CCPrioritizedTexture::Backing* b)
     {
-        int priorityA = a->owner() ? a->owner()->requestPriority() : CCPriorityCalculator::lowestPriority();
-        int priorityB = b->owner() ? b->owner()->requestPriority() : CCPriorityCalculator::lowestPriority();
-        if (priorityA == priorityB)
-            return a < b;
-        return CCPriorityCalculator::priorityIsLower(priorityA, priorityB);
+        int priorityA = a->requestPriorityAtLastPriorityUpdate();
+        int priorityB = b->requestPriorityAtLastPriorityUpdate();
+        if (priorityA != priorityB)
+            return CCPriorityCalculator::priorityIsLower(priorityA, priorityB);
+        bool aboveCutoffA = a->wasAbovePriorityCutoffAtLastPriorityUpdate();
+        bool aboveCutoffB = b->wasAbovePriorityCutoffAtLastPriorityUpdate();
+        if (!aboveCutoffA && aboveCutoffB)
+            return true;
+        if (aboveCutoffA && !aboveCutoffB)
+            return false;
+        return a < b;
     }
 
     CCPrioritizedTextureManager(size_t maxMemoryLimitBytes, int maxTextureSize, int pool);
 
-    void reduceMemory(size_t limit, CCResourceProvider*);
-
+    void updateBackingsPriorities();
+    void evictBackingsToReduceMemory(size_t limitBytes, EvictionPriorityPolicy, CCResourceProvider*);
     CCPrioritizedTexture::Backing* createBacking(IntSize, GC3Denum format, CCResourceProvider*);
-    void destroyBacking(CCPrioritizedTexture::Backing*, CCResourceProvider*);
+    void evictBackingResource(CCPrioritizedTexture::Backing*, CCResourceProvider*);
+
+#if !ASSERT_DISABLED
+    void assertInvariants();
+#endif
 
     size_t m_maxMemoryLimitBytes;
     unsigned m_priorityCutoff;
@@ -106,13 +127,17 @@ private:
     typedef HashSet<CCPrioritizedTexture*> TextureSet;
     typedef ListHashSet<CCPrioritizedTexture::Backing*> BackingSet;
     typedef Vector<CCPrioritizedTexture*> TextureVector;
-    typedef Vector<CCPrioritizedTexture::Backing*> BackingVector;
 
     TextureSet m_textures;
     BackingSet m_backings;
+    BackingVector m_evictedBackings;
 
     TextureVector m_tempTextureVector;
     BackingVector m_tempBackingVector;
+
+    // Set by the main thread when it adjust priorities in such a way that
+    // the m_backings array's view of priorities is now out of date.
+    bool m_needsUpdateBackingsPrioritites;
 };
 
 } // cc