Implemented support for GL constext share groups in the renderer process.

gpu/command_buffer/service/gles2_cmd_decoder_unittest.cc

Index: gpu/command_buffer/service/gles2_cmd_decoder_unittest.cc
===================================================================
--- gpu/command_buffer/service/gles2_cmd_decoder_unittest.cc	(revision 95161)
+++ gpu/command_buffer/service/gles2_cmd_decoder_unittest.cc	(working copy)
@@ -2310,7 +2310,7 @@
   GLuint* ids = GetSharedMemoryAs<GLuint*>();
   gen_cmd.Init(kNamespaceId, 0, 2, kSharedMemoryId, kSharedMemoryOffset);
   EXPECT_EQ(error::kNoError, ExecuteCmd(gen_cmd));
-  IdAllocator* id_allocator = GetIdAllocator(kNamespaceId);
+  IdAllocatorInterface* id_allocator = GetIdAllocator(kNamespaceId);
   ASSERT_TRUE(id_allocator != NULL);
   // This check is implementation dependant but it's kind of hard to check
   // otherwise.