Enable UpdateProcessPriority() on startup on Chrome OS.

content/browser/renderer_host/render_process_host_impl.cc

 // 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.
 
 // Represents the browser side of the browser <--> renderer communication
 // channel. There will be one RenderProcessHost per renderer process.
 
 #include "content/browser/renderer_host/render_process_host_impl.h"
 
 #include <algorithm>
@@ skipping 2594 matching lines @@
     // sure |is_process_backgrounded_| reflects this platform's initial process
     // state.
     is_process_backgrounded_ =
         child_process_launcher_->GetProcess().IsProcessBackgrounded();
 
     // Disable updating process priority on startup for now as it incorrectly
     // results in backgrounding foreground navigations until their first commit
     // is made. A better long term solution would be to be aware of the tab's
     // visibility at this point. https://crbug.com/560446.
     // Except on Android for now because of https://crbug.com/601184 :-(.
-#if defined(OS_ANDROID)
+    // The exception also applies to Chrome OS: https://crbug.com/601023.
+#if defined(OS_ANDROID) || defined(OS_CHROMEOS)

[rjkroege, 2016/04/18 17:06:07]

I am not convinced that this is the right place for this functionality
especially as we mojo-i-fy CrOS chrome.

     UpdateProcessPriority();
 #endif
 
     // Share histograms between the renderer and this process.
     CreateSharedRendererHistogramAllocator();
   }
 
   // NOTE: This needs to be before sending queued messages because
   // ExtensionService uses this notification to initialize the renderer process
   // with state that must be there before any JavaScript executes.
@@ skipping 216 matching lines @@
 
     // Skip widgets in other processes.
     if (rvh->GetProcess()->GetID() != GetID())
       continue;
 
     rvh->OnWebkitPreferencesChanged();
   }
 }
 
 }  // namespace content