Add the ability to clear the shader disk cache.

content/content_browser.gypi

Index: content/content_browser.gypi
diff --git a/content/content_browser.gypi b/content/content_browser.gypi
index b82d96e25d209460ed227b4a6721e4e2d34b8884..260bafc20d460102b9749ffc341690b84dca6580 100644
--- a/content/content_browser.gypi
+++ b/content/content_browser.gypi
@@ -145,6 +145,8 @@
     'public/browser/resource_throttle.h',
     'public/browser/save_page_type.h',
     'public/browser/session_storage_namespace.h',
+    'public/browser/shader_disk_cache.cc',
+    'public/browser/shader_disk_cache.h',
     'public/browser/site_instance.h',
     'public/browser/speech_recognition_event_listener.h',
     'public/browser/speech_recognition_manager.h',
@@ -492,8 +494,8 @@
     'browser/gpu/gpu_surface_tracker.h',
     'browser/gpu/gpu_util.cc',
     'browser/gpu/gpu_util.h',
-    'browser/gpu/shader_disk_cache.cc',
-    'browser/gpu/shader_disk_cache.h',
+    'browser/gpu/shader_disk_cache_impl.cc',
+    'browser/gpu/shader_disk_cache_impl.h',
     'browser/histogram_controller.cc',
     'browser/histogram_controller.h',
     'browser/histogram_internals_request_job.cc',