Revert of Idle cleanup for worker context

cc/output/context_cache_controller.h

 // Copyright (c) 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CC_OUTPUT_CONTEXT_CACHE_CONTROLLER_H_
 #define CC_OUTPUT_CONTEXT_CACHE_CONTROLLER_H_
 
 #include <cstdint>
 #include <memory>
 
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
-#include "base/memory/weak_ptr.h"
 #include "cc/base/cc_export.h"
 
 class GrContext;
 
 namespace base {
-class Lock;
 class SingleThreadTaskRunner;
 }
 
 namespace gpu {
 class ContextSupport;
 }
 
 namespace cc {
 
 // ContextCacheController manages clearing cached data on ContextProvider when
-// appropriate. Currently, cache clearing is triggered when the Context
-// provider transitions from Visible to Not Visible, or from Busy to Idle. As a
-// ContextProvider may have multiple clients, ContextCacheController tracks
-// visibility and idle status across all clients and only cleans up when
-// appropriate.
+// appropriate. Currently, cache clearing happens when the ContextProvider
+// transitions from visible to not visible. As a ContextProvider may have
+// multiple clients, ContextCacheController tracks visibility across all
+// clients and only cleans up when appropriate.
+//
+// Note: Virtuals on this function are for testing only. This function is not
+// designed to have multiple implementations.
 class CC_EXPORT ContextCacheController {
  public:
-  class CC_EXPORT ScopedToken {
+  class CC_EXPORT ScopedVisibility {
    public:
-    ~ScopedToken();
+    ~ScopedVisibility();
 
    private:
     friend class ContextCacheController;
-    ScopedToken();
+    ScopedVisibility();
     void Release();
 
     bool released_ = false;
   };
-  using ScopedVisibility = ScopedToken;
-  using ScopedBusy = ScopedToken;
 
   ContextCacheController(
       gpu::ContextSupport* context_support,
       scoped_refptr<base::SingleThreadTaskRunner> task_runner);
   virtual ~ContextCacheController();
 
   void SetGrContext(GrContext* gr_context);
-  void SetLock(base::Lock* lock);
 
   // Clients of the owning ContextProvider should call this function when they
   // become visible. The returned ScopedVisibility pointer must be passed back
   // to ClientBecameNotVisible or it will DCHECK in its destructor.
   virtual std::unique_ptr<ScopedVisibility> ClientBecameVisible();
 
   // When a client becomes not visible (either due to a visibility change or
   // because it is being deleted), it must pass back any ScopedVisibility
   // pointers it owns via this function.
   virtual void ClientBecameNotVisible(
       std::unique_ptr<ScopedVisibility> scoped_visibility);
 
-  // Clients of the owning ContextProvider may call this function when they
-  // become busy. The returned ScopedBusy pointer must be passed back
-  // to ClientBecameNotBusy or it will DCHECK in its destructor.
-  std::unique_ptr<ScopedBusy> ClientBecameBusy();
-
-  // When a client becomes not busy, it must pass back any ScopedBusy
-  // pointers it owns via this function.
-  void ClientBecameNotBusy(std::unique_ptr<ScopedBusy> scoped_busy);
+ protected:
+  std::unique_ptr<ScopedVisibility> CreateScopedVisibilityForTesting() const;
+  void ReleaseScopedVisibilityForTesting(
+      std::unique_ptr<ScopedVisibility> scoped_visibility) const;
 
  private:
-  void OnIdle(uint32_t idle_generation);
-  void PostIdleCallback(uint32_t current_idle_generation) const;
-  void InvalidatePendingIdleCallbacks();
-
   gpu::ContextSupport* context_support_;
   scoped_refptr<base::SingleThreadTaskRunner> task_runner_;
   GrContext* gr_context_ = nullptr;
 
-  // If set, |context_lock_| must be held before accessing any member within
-  // the idle callback. Exceptions to this are |current_idle_generation_|,
-  // which has its own lock, and weak_ptr_ and task_runner_, which may be
-  // accessed from multiple threads without locking.
-  base::Lock* context_lock_ = nullptr;
-
   uint32_t num_clients_visible_ = 0;
-  uint32_t num_clients_busy_ = 0;
-  bool callback_pending_ = false;
-
-  // |current_idle_generation_lock_| must be held when accessing
-  // |current_idle_generation_|. |current_idle_generation_lock_| must never be
-  // held while acquiring |context_lock_|.
-  base::Lock current_idle_generation_lock_;
-  uint32_t current_idle_generation_ = 0;
-
-  base::WeakPtr<ContextCacheController> weak_ptr_;
-  base::WeakPtrFactory<ContextCacheController> weak_factory_;
 };
 
 }  // namespace cc
 
 #endif  // CC_OUTPUT_CONTEXT_CACHE_CONTROLLER_H_