Use GpuPreferences to avoid directly accessing switches in gpu related code

gpu/command_buffer/service/memory_program_cache.h

Index: gpu/command_buffer/service/memory_program_cache.h
diff --git a/gpu/command_buffer/service/memory_program_cache.h b/gpu/command_buffer/service/memory_program_cache.h
index 73115d8b662de34971130122d22f4d8fccf3a00b..635f8ab3af87a96a367b5db865c0caedf535d322 100644
--- a/gpu/command_buffer/service/memory_program_cache.h
+++ b/gpu/command_buffer/service/memory_program_cache.h
@@ -19,13 +19,16 @@
 #include "gpu/command_buffer/service/program_cache.h"
 
 namespace gpu {
+
+struct GpuPreferences;
+
 namespace gles2 {
 
 // Program cache that stores binaries completely in-memory
 class GPU_EXPORT MemoryProgramCache : public ProgramCache {
  public:
-  MemoryProgramCache();
-  explicit MemoryProgramCache(const size_t max_cache_size_bytes);
+  MemoryProgramCache(const size_t max_cache_size_bytes,
+                     const bool disable_gpu_shader_disk_cache);

[piman, 2016/02/24 22:19:08]

nit: no const in the parameters, unless they're references/pointers.

[Peng, 2016/02/25 16:18:36]

Done.

   ~MemoryProgramCache() override;
 
   ProgramLoadResult LoadLinkedProgram(
@@ -150,6 +153,7 @@ class GPU_EXPORT MemoryProgramCache : public ProgramCache {
                          scoped_refptr<ProgramCacheValue> > ProgramMRUCache;
 
   const size_t max_size_bytes_;
+  const bool disable_gpu_shader_disk_cache_;
   size_t curr_size_bytes_;
   ProgramMRUCache store_;