gpu: Generate mailboxes on client side

cc/test/test_web_graphics_context_3d.h

Index: cc/test/test_web_graphics_context_3d.h
diff --git a/cc/test/test_web_graphics_context_3d.h b/cc/test/test_web_graphics_context_3d.h
index 1300a8f181a2fa6998320a33318b45da9f3d2005..39f87672ff606b0dd3454caff7b3d0db4bd59dab 100644
--- a/cc/test/test_web_graphics_context_3d.h
+++ b/cc/test/test_web_graphics_context_3d.h
@@ -263,9 +263,6 @@ class TestWebGraphicsContext3D {
   void set_times_end_query_succeeds(int times) {
     times_end_query_succeeds_ = times;
   }
-  void set_times_gen_mailbox_succeeds(int times) {
-    times_gen_mailbox_succeeds_ = times;
-  }
 
   // When set, mapImageCHROMIUM and mapBufferCHROMIUM will return NULL after
   // this many times.
@@ -414,7 +411,6 @@ class TestWebGraphicsContext3D {
   ContextProvider::Capabilities test_capabilities_;
   int times_bind_texture_succeeds_;
   int times_end_query_succeeds_;
-  int times_gen_mailbox_succeeds_;
   bool context_lost_;
   int times_map_image_chromium_succeeds_;
   int times_map_buffer_chromium_succeeds_;