content: Improve thread priority for raster threads.

content/browser/gpu/compositor_util.cc

 // 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.
 
 #include "content/browser/gpu/compositor_util.h"
 
 #include <stddef.h>
 
 #include "base/command_line.h"
 #include "base/logging.h"
@@ skipping 151 matching lines @@
 
 }  // namespace
 
 bool IsPropertyTreeVerificationEnabled() {
   const base::CommandLine& command_line =
       *base::CommandLine::ForCurrentProcess();
   return command_line.HasSwitch(cc::switches::kEnablePropertyTreeVerification);
 }
 
 int NumberOfRendererRasterThreads() {
-  int num_processors = base::SysInfo::NumberOfProcessors();
+  int num_raster_threads = base::SysInfo::NumberOfProcessors() / 2;
 
 #if defined(OS_ANDROID)
-  // Android may report 6 to 8 CPUs for big.LITTLE configurations.
-  // Limit the number of raster threads based on maximum of 4 big cores.
-  num_processors = std::min(num_processors, 4);
-#endif
-
-  int num_raster_threads = num_processors / 2;
-
-#if defined(OS_ANDROID)
-  // Limit the number of raster threads to 1 on Android.
-  // TODO(reveman): Remove this when we have a better mechanims to prevent
-  // pre-paint raster work from slowing down non-raster work. crbug.com/504515
+  // Use one thread for foreground raster work on Android.
   num_raster_threads = 1;
 #endif
 
   const base::CommandLine& command_line =
       *base::CommandLine::ForCurrentProcess();
 
   if (command_line.HasSwitch(switches::kNumRasterThreads)) {
     std::string string_value = command_line.GetSwitchValueASCII(
         switches::kNumRasterThreads);
     if (!base::StringToInt(string_value, &num_raster_threads)) {
@@ skipping 200 matching lines @@
     }
   }
   return problem_list;
 }
 
 std::vector<std::string> GetDriverBugWorkarounds() {
   return GpuDataManagerImpl::GetInstance()->GetDriverBugWorkarounds();
 }
 
 }  // namespace content