Use GpuPreferences to avoid directly accessing switches in gpu related code

content/gpu/in_process_gpu_thread.h

Index: content/gpu/in_process_gpu_thread.h
diff --git a/content/gpu/in_process_gpu_thread.h b/content/gpu/in_process_gpu_thread.h
index 49eda00efaf4c01cd34db5f12eafd866d603cd2f..6acb7a5f9629b83244f1f2abb534b94a28ff7311 100644
--- a/content/gpu/in_process_gpu_thread.h
+++ b/content/gpu/in_process_gpu_thread.h
@@ -11,6 +11,7 @@
 #include "content/common/in_process_child_thread_params.h"
 
 namespace gpu {
+struct GpuPreferences;
 class SyncPointManager;
 }
 
@@ -24,6 +25,7 @@ class GpuProcess;
 class InProcessGpuThread : public base::Thread {
  public:
   InProcessGpuThread(const InProcessChildThreadParams& params,
+                     const gpu::GpuPreferences* gpu_preferences,
                      gpu::SyncPointManager* sync_point_manager_override);
   ~InProcessGpuThread() override;
 
@@ -37,6 +39,8 @@ class InProcessGpuThread : public base::Thread {
   // Deleted in CleanUp() on the gpu thread, so don't use smart pointers.
   GpuProcess* gpu_process_;
 
+  const gpu::GpuPreferences* const gpu_preferences_;
+
   // Can be null if overridden.
   scoped_ptr<gpu::SyncPointManager> sync_point_manager_;