Revert of Support impl-side painting in Mandoline.

components/html_viewer/discardable_memory_allocator.h

Index: components/html_viewer/discardable_memory_allocator.h
diff --git a/components/html_viewer/discardable_memory_allocator.h b/components/html_viewer/discardable_memory_allocator.h
index 9be0e212d1982628cfc8a08b0d881232a320035d..be7f063ef9064fb9e3dcaa2fc87057bfd7b3570a 100644
--- a/components/html_viewer/discardable_memory_allocator.h
+++ b/components/html_viewer/discardable_memory_allocator.h
@@ -8,7 +8,6 @@
 #include <list>
 
 #include "base/memory/discardable_memory_allocator.h"
-#include "base/synchronization/lock.h"
 
 namespace html_viewer {
 
@@ -16,6 +15,8 @@
 // allocations.
 class DiscardableMemoryAllocator : public base::DiscardableMemoryAllocator {
  public:
+  class OwnedMemoryChunk;
+
   explicit DiscardableMemoryAllocator(size_t desired_max_memory);
   ~DiscardableMemoryAllocator() override;
 
@@ -24,31 +25,22 @@
       size_t size) override;
 
  private:
-  class DiscardableMemoryChunkImpl;
-  friend class DiscardableMemoryChunkImpl;
+  friend class OwnedMemoryChunk;
 
-  // Called by DiscardableMemoryChunkImpl when they are unlocked. This puts them
-  // at the end of the live_unlocked_chunks_ list and passes an iterator to
-  // their position in the unlocked chunk list.
-  std::list<DiscardableMemoryChunkImpl*>::iterator NotifyUnlocked(
-      DiscardableMemoryChunkImpl* chunk);
+  // Called by OwnedMemoryChunks when they are unlocked. This puts them at the
+  // end of the live_unlocked_chunks_ list and passes an iterator to their
+  // position in the unlocked chunk list.
+  std::list<OwnedMemoryChunk*>::iterator NotifyUnlocked(
+      OwnedMemoryChunk* chunk);
 
-  // Called by DiscardableMemoryChunkImpl when they are locked. This removes the
-  // passed in unlocked chunk list.
-  void NotifyLocked(std::list<DiscardableMemoryChunkImpl*>::iterator it);
-
-  // Called by DiscardableMemoryChunkImpl when it's destructed. It must be
-  // unlocked, by definition.
-  void NotifyDestructed(std::list<DiscardableMemoryChunkImpl*>::iterator it);
+  // Called by OwnedMemoryChunks when they are locked. This removes the passed
+  // in unlocked chunk list.
+  void NotifyLocked(std::list<OwnedMemoryChunk*>::iterator it);
 
   // The amount of memory we can allocate before we try to free unlocked
   // chunks. We can go over this amount if all callers keep their discardable
   // chunks locked.
   const size_t desired_max_memory_;
-
-  // Protects all members below, since this class can be called on the main
-  // thread and impl side painting raster threads.
-  base::Lock lock_;
 
   // A count of the sum of memory. Used to trigger discarding the oldest
   // memory.
@@ -59,7 +51,7 @@
 
   // A linked list of unlocked allocated chunks so that the tail is most
   // recently accessed chunks.
-  std::list<DiscardableMemoryChunkImpl*> live_unlocked_chunks_;
+  std::list<OwnedMemoryChunk*> live_unlocked_chunks_;
 
   DISALLOW_COPY_AND_ASSIGN(DiscardableMemoryAllocator);
 };