Revert of Remove ForceReclaimResources

cc/output/compositor_frame_sink.h

 // Copyright 2012 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_COMPOSITOR_FRAME_SINK_H_
 #define CC_OUTPUT_COMPOSITOR_FRAME_SINK_H_
 
 #include <deque>
 #include <memory>
 
@@ skipping 22 matching lines @@
 // which will compose frames from multiple CompositorFrameSinks to show
 // on screen to the user.
 // If a context_provider() is present, frames should be submitted with
 // OpenGL resources (created with the context_provider()). If not, then
 // SharedBitmap resources should be used.
 class CC_EXPORT CompositorFrameSink {
  public:
   struct Capabilities {
     Capabilities() = default;
 
-    // True if we must always swap, even if there is no damage to the frame.
-    // Needed for both the browser compositor as well as layout tests.
-    // TODO(ericrk): This should be test-only for layout tests, but tab
-    // capture has issues capturing offscreen tabs whithout this. We should
-    // remove this dependency. crbug.com/680196
-    bool must_always_swap = false;
-
+    // Whether ForceReclaimResources can be called to reclaim all resources
+    // from the CompositorFrameSink.
+    bool can_force_reclaim_resources = false;
     // True if sync points for resources are needed when swapping delegated
     // frames.
     bool delegated_sync_points_required = true;
   };
 
   // Constructor for GL-based and/or software resources.
   // gpu_memory_buffer_manager and shared_bitmap_manager must outlive the
   // CompositorFrameSink.
   // shared_bitmap_manager is optional (won't be used) if context_provider is
   // present.
@@ skipping 38 matching lines @@
   VulkanContextProvider* vulkan_context_provider() const {
     return vulkan_context_provider_.get();
   }
   gpu::GpuMemoryBufferManager* gpu_memory_buffer_manager() const {
     return gpu_memory_buffer_manager_;
   }
   SharedBitmapManager* shared_bitmap_manager() const {
     return shared_bitmap_manager_;
   }
 
+  // If supported, this causes a ReclaimResources for all resources that are
+  // currently in use.
+  virtual void ForceReclaimResources() {}
+
   // Support for a pull-model where draws are requested by the output surface.
   //
   // CompositorFrameSink::Invalidate is called by the compositor to notify that
   // there's new content.
   virtual void Invalidate() {}
 
   // For successful swaps, the implementation must call
   // DidReceiveCompositorFrameAck() asynchronously when the frame has been
   // processed in order to unthrottle the next frame.
   virtual void SubmitCompositorFrame(CompositorFrame frame) = 0;
@@ skipping 13 matching lines @@
   SharedBitmapManager* shared_bitmap_manager_;
   base::ThreadChecker client_thread_checker_;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(CompositorFrameSink);
 };
 
 }  // namespace cc
 
 #endif  // CC_OUTPUT_COMPOSITOR_FRAME_SINK_H_