Revert workaround due to perf regression

content/browser/gpu/gpu_data_manager_impl_private.cc

 // Copyright (c) 2013 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/gpu_data_manager_impl_private.h"
 
 #include <algorithm>
 #include <iterator>
 #include <memory>
 #include <utility>
@@ skipping 859 matching lines @@
 
   const base::CommandLine* command_line =
       base::CommandLine::ForCurrentProcess();
   if (!ShouldDisableAcceleratedVideoDecode(command_line) &&
       !command_line->HasSwitch(switches::kDisableAcceleratedVideoDecode)) {
     prefs->pepper_accelerated_video_decode_enabled = true;
   }
   prefs->disable_2d_canvas_copy_on_write =
       IsDriverBugWorkaroundActive(gpu::BROKEN_EGL_IMAGE_REF_COUNTING) &&
       command_line->HasSwitch(switches::kEnableThreadedTextureMailboxes);
-  prefs->force_software_readback_from_2d_canvas =
-      IsDriverBugWorkaroundActive(gpu::FORCE_SOFTWARE_READBACK_FROM_2D_CANVAS);
 }
 
 void GpuDataManagerImplPrivate::DisableHardwareAcceleration() {
   if (!is_initialized_) {
     post_init_tasks_.push_back(
         base::Bind(&GpuDataManagerImplPrivate::DisableHardwareAcceleration,
                    base::Unretained(this)));
     return;
   }
 
@@ skipping 431 matching lines @@
   gpu_info_.context_info_state = gpu::kCollectInfoFatalFailure;
 #if defined(OS_WIN)
   gpu_info_.dx_diagnostics_info_state = gpu::kCollectInfoFatalFailure;
 #endif
   complete_gpu_info_already_requested_ = true;
   // Some observers might be waiting.
   NotifyGpuInfoUpdate();
 }
 
 }  // namespace content