Proposed new approach for SetBackgrounded.

content/browser/renderer_host/render_process_host_impl.h

 // Copyright (c) 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 CONTENT_BROWSER_RENDERER_HOST_RENDER_PROCESS_HOST_IMPL_H_
 #define CONTENT_BROWSER_RENDERER_HOST_RENDER_PROCESS_HOST_IMPL_H_
 
 #include <map>
 #include <queue>
 #include <string>
@@ skipping 311 matching lines @@
   // results to |*command_line|.
   void AppendRendererCommandLine(base::CommandLine* command_line) const;
 
   // Copies applicable command line switches from the given |browser_cmd| line
   // flags to the output |renderer_cmd| line flags. Not all switches will be
   // copied over.
   void PropagateBrowserCommandLineToRenderer(
       const base::CommandLine& browser_cmd,
       base::CommandLine* renderer_cmd) const;
 
-  // Callers can reduce the RenderProcess' priority.
-  void SetBackgrounded(bool backgrounded);
+  // Inspects the current object state and sets/removes background priority if
+  // appropriate. Should be called after any of the involved data members
+  // change.
+  void UpdateProcessPriority();
 
   // Handle termination of our process.
   void ProcessDied(bool already_dead, RendererClosedDetails* known_details);
 
   // GpuSwitchingObserver implementation.
   void OnGpuSwitched() override;
 
 #if defined(ENABLE_WEBRTC)
   void OnRegisterAecDumpConsumer(int id);
   void OnUnregisterAecDumpConsumer(int id);
@@ skipping 10 matching lines @@
 
   // The registered IPC listener objects. When this list is empty, we should
   // delete ourselves.
   IDMap<IPC::Listener> listeners_;
 
   // The count of currently visible widgets.  Since the host can be a container
   // for multiple widgets, it uses this count to determine when it should be
   // backgrounded.
   int32 visible_widgets_;
 
-  // Does this process have backgrounded priority.
-  bool backgrounded_;
+  // Whether this process currently has backgrounded priority. Tracked so that
+  // UpdateProcessPriority() can avoid redundantly setting the priority.
+  bool is_process_backgrounded_;
 
   // Used to allow a RenderWidgetHost to intercept various messages on the
   // IO thread.
   scoped_refptr<RenderWidgetHelper> widget_helper_;
 
   // The filter for GPU-related messages coming from the renderer.
   // Thread safety note: this field is to be accessed from the UI thread.
   // We don't keep a reference to it, to avoid it being destroyed on the UI
   // thread, but we clear this field when we clear channel_. When channel_ goes
   // away, it posts a task to the IO thread to destroy it there, so we know that
@@ skipping 132 matching lines @@
 #endif
 
   base::WeakPtrFactory<RenderProcessHostImpl> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(RenderProcessHostImpl);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_RENDERER_HOST_RENDER_PROCESS_HOST_IMPL_H_