base: Allow renderer thread priorities to be changed.

content/child/child_thread_impl.h

Index: content/child/child_thread_impl.h
diff --git a/content/child/child_thread_impl.h b/content/child/child_thread_impl.h
index a66506aac5d5b40543b4381b7c933372cd31c29f..67e0343a1af4d791fd2ef9f33762d206c14e33e3 100644
--- a/content/child/child_thread_impl.h
+++ b/content/child/child_thread_impl.h
@@ -121,6 +121,11 @@ class CONTENT_EXPORT ChildThreadImpl
       IPC::Sender* sender,
       bool* out_of_memory);
 
+#if defined(OS_LINUX)
+  void SetThreadPriority(base::PlatformThreadId id,
+                         base::ThreadPriority priority);
+#endif
+
   ChildSharedBitmapManager* shared_bitmap_manager() const {
     return shared_bitmap_manager_.get();
   }