gpu: Use a rectangle to keep track of the cleared area of each texture level.

gpu/command_buffer/service/gles2_cmd_decoder_mock.h

Index: gpu/command_buffer/service/gles2_cmd_decoder_mock.h
diff --git a/gpu/command_buffer/service/gles2_cmd_decoder_mock.h b/gpu/command_buffer/service/gles2_cmd_decoder_mock.h
index 65df53c53dfdc02646ed27a10df1066c6792b281..e619f6be3a159e75cad926bf63636d7320391a56 100644
--- a/gpu/command_buffer/service/gles2_cmd_decoder_mock.h
+++ b/gpu/command_buffer/service/gles2_cmd_decoder_mock.h
@@ -101,16 +101,16 @@ class MockGLES2Decoder : public GLES2Decoder {
                                          uint32* service_texture_id));
   MOCK_METHOD0(GetContextLostReason, error::ContextLostReason());
   MOCK_CONST_METHOD1(GetCommandName, const char*(unsigned int command_id));
-  MOCK_METHOD9(ClearLevel, bool(
-      Texture* texture,
-      unsigned target,
-      int level,
-      unsigned internal_format,
-      unsigned format,
-      unsigned type,
-      int width,
-      int height,
-      bool is_texture_immutable));
+  MOCK_METHOD9(ClearLevel,
+               bool(Texture* texture,
+                    unsigned target,
+                    int level,
+                    unsigned format,
+                    unsigned type,
+                    int x_offset,
+                    int y_offset,
+                    int width,
+                    int height));
   MOCK_METHOD0(GetErrorState, ErrorState *());
 
   MOCK_METHOD0(GetLogger, Logger*());